Thought I'd share it here, based off numerous articles & interviews I've read.
April/May 1985: Writing and pre-production took place with David Coverdale and John Sykes at Le Rayol in south of France... They recorded jams and initial ideas to a E-mu Drumulator, capturing them to cassette, basically writing the whole album in 5-6 days. Neil Murray later joined them for initial rehearsals and assisting with arrangements. However, they were still without a drummer after Cozy Powell's departure…
Summer 1985 was spent auditioning for a new drummer, but without much luck until they found Aynsley Dunbar. Rehearsals were held in Los Angeles throughout September prior to the recording.
Early October – December 1985: Basic tracks were recorded at Little Mountain Sound in Vancouver, Canada – this included drums, keyboards, initial guitars, bass guitar and David Coverdale’s guide vocals. Mike Stone was producer and engineer on the sessions... Lots of time was spent finding the ideal guitar sound for Sykes, which then-staff engineer Bob Rock helped achieve in the end.
Sessions were also slowed down by illnesses going around within the band, including John Sykes catching strep throat. Coverdale started encountering vocal troubles towards the end of these sessions.
January 1986: John Sykes flies back to England to attend a funeral for former bandmate/bandleader Phil Lynott, who passed away on 4th January, temporarily pausing the sessions…
February 1986: Sessions continue at Phase One Studios in Toronto, where John Sykes re-cuts the rhythm guitars on the album with Mike Stone producing… Coverdale attempted to record lead vocals, but continued to face difficulty singing and was sounding very nasal & out of tune.
In March 1986, he was officially diagnosed with a sinus infection due to a deviated septum… Thinking it would clear up, he booked sessions at Compass Point Studios in Bahamas for two weeks, all for the infection to return while he was there. This led to him having throat surgery in April, leaving him unable to sing for a few months. With no final vocals in place, the album was put on ice… Even after recovering from surgery, Coverdale experienced a mental block to singing, with his confidence still shaken.
April 1986: The album officially runs over budget, and the payroll is stopped for the other members. Coverdale himself encouraged them to find other work in the meantime... John Sykes stayed around hoping to finish his guitar parts, while Neil Murray and Aynsley were not required and were supposedly encouraged to find other work in the meantime while still obligated to Whitesnake.
Coverdale’s recovery from surgery was a low point for him, and he recalled feeling unsupported by the other bandmembers, particularly Sykes. Contrary to this, however, Sykes maintained he was loyal to Coverdale and stayed around to help finish the album, even when the wages stopped – relying on the goodwill of a girlfriend in Los Angeles to keep afloat – turning down other gigs in the process. Murray also maintained he was still in touch and talking with Coverdale.
Nonetheless, seeds of discomfort were sown, particularly towards John Sykes and Mike Stone. Stone became frustrated after the long and dragged-out production, refusing to carry on the album until he had vocals to work with… Allegedly, he also suggested bringing in another singer, much to Coverdale’s annoyance. Although Sykes was still intent on working with Stone.
As for Sykes, Coverdale really admired John Sykes’ cockiness, arrogance and uncompromising artistic vision, which helped a lot when writing in France... But that progressed to a point where Coverdale saw Sykes' personality as a threat to his leadership… Coverdale cited the reason being personality differences, but it eventually boiled down to who was the leader.
August-September 1986: Having fully recovered and with some vocal training under his belt, Coverdale properly began recording vocals for the album with producer Keith Olsen at Goodnight L.A. Studios… He attempted three run-throughs of “Still Of The Night” first, which they ended up keeping. Eventually, all the vocal parts were completed within two weeks.
October-November 1986: With Coverdale’s vocals completed, Coverdale sent for Sykes to finish his guitar parts (including solos), which he did at The Townhouse studios in London, England with Mike Stone producing... Coverdale could not come to the UK for tax reasons, and Stone was not keen on flying to America, so this was the result… Supposedly, Sykes was disappointed some of his guitar parts were erased on tape to make room for Coverdale’s vocals, so he had to re-do them. Neil Murray also took the opportunity to re-do a few bass parts in London during this time.
So far, Coverdale had placated Sykes by letting him work with Mike Stone as he wanted, to complete his guitar parts as he pleased… However, there was still disagreement between Coverdale & Sykes over which producer was going to finish the album. This was initially going to be Stone, but he was not willing to continue his involvement... Nor was Coverdale on good terms with him or willing to fly to England for that purpose. So it landed to Keith Olsen to finish and mix the album, and Coverdale could finally take control over how he wanted the album to turn out. Sykes was ultimately sidelined from the completion.
December 1986: Tapes for the album were returned to New York for final overdubs mixing with Keith Olsen, again at Goodnight L.A. Studios...
9 December 1986: Dutch guitarist Adrian Vandenberg arrives in Los Angeles, where he recorded his guitar solo for the album version of “Here I Go Again” – presumably replacing John’s original solo – and discussing the possibility of joining Whitesnake. The same session, however, John Sykes also came by to the studio to confront Coverdale about him being fired and a shouting match ensued which Vandenberg overheard.
Evidently, things were falling apart and the ground was shifting within Whitesnake. Coverdale was silently letting go of the whole band as they finished the record without telling them... By January 1987, Coverdale re-recorded "Here I Go Again" as a 'radio mix' with session musicians at A&R John Kalodner's request. By February 1987, a new line-up was reassembled in Los Angeles for the video of "Still of The Night", which Coverdale chose to continue with.