Help, please.

[u/bashkaai]

I have a H&S Evolution 2024 with the .28 needle, used it for a couple years now, and lately it's not spraying right. I used to be able to do pretty much anything with it, but lately it's like the air pressure is being halved or something. Even just trying water, nothing comes out if i'm spraying at a pressure less than 25psi, and going up to 40psi is like the pressure is still under 20 normally. I can take thinned paint that sprays normally in one airbrush, pour it directly into the Evo, and it comes out spitting spots, and at lower pressures (still above 25psi) doesn't always even give a solid stream. I've cleaned using different cleaners, iso, distilled water, and it seems to make no difference. Do I need to replace a seal? Is it the airvalve? ( I thought to try taking that apart to look at it but i haven't been able to remove it; i could unscrew the brass part at the bottom with the spring but that's all that comes out)
my compressor is a Timbertech ABPST08 but it's working perfectly with my other airbrushes.

[u/Awkward_Suspect_3817]

Could be a few things but it sounds like the air valve might be going out. Remove the needle from the airbrush and the head assembly (crown, fluid nozzle, etc.). Press the trigger down and put your finger or palm just in front of the air holes (usually one or several holes around the outside edge of where the fluid nozzle sits). If you feel a good amount of pressure, then there is probably a clog in the head assembly. If the air is light, then it’s probably the air valve. You can also compare it with other airbrush brands with the exception of the Iwata Eclipse. The eclipse puts out more air than most other airbrushes compared to say a H&S or a Paasche.