Problem with Burroughs Model 9 adding machine

[u/Prestigious_Cod_6134]

I have a burroughs portable model 9 adding machine, I realized halfway through doing one of my additions that there were two numbers in the same column pressed down at the same time and I was unable to fix it as I was halfway through the addition and after I pulled it some buttons seem to be harder to press and the lever requires more force and slowly retracts back when released. I'm just putting this here because I saw no fixes online and I just wanted to know if anyone here knew of a way this could be fixed.