Hello. I have a 2000 Emglo GT electric compressor. It's hardwired and well maintained, but has recently started struggling once it hits between 60 & 90 psi. It huffs and puffs, the belt squeals and the motor slows down, it seems like there's a blockage somewhere. It eventually gets to 175 & shuts off, but it takes a while. This last time, though, since I checked the check valve and the pipe (there were no problems there), I started from 0, and it only got to 90. I removed the oil fill plug to check for blow-by, but at that time, it never started struggling and went to 175 smoothly. Is it possibly a sticking exhaust valve? I am interested in buying a valve job kit from Master Tool Repair if this is the likely cause. Thanks!