I just got my oven together and took my gun (Caswell) out of the box. I got the gun in the mail earlier this week. I applied the recommended PSI and it worked for about 2 seconds. I ended up taking the whole thing (gun) apart and thoroughly cleaning. It looks like the OEM lube turns gummy/crusty and clogs things and makes all the moving parts move like ass (I have pics of the crusty/gummy parts).
I agree with the 30-40PSI recommendation. 10-15PSI will not operate my gun sufficiently. I also used petroleum/Vaseline in very light amounts for my lube. The stickiness is from the O-rings binding on there respective shafts. In my case both the trigger and the fine PSI adjuster were very sticky. The seat and valve on my fine adjuster were both full of crusty nasty gunk right out of the box. Stronger return springs (trigger and fine PSI), clean up all the burrs/crust/gummy OEM lube (thread sealant maybe?), and it works ok....
Caswell should re-think there supplier, or re-design the gun and get a new vendor. It is obvious that at least the gun portion is an off the shelf lowest bidder type item.... I paid over $200 for this thing and I had to disassemble, clean, inspect, lube, and re-assemble before I can even think about using it, WTF?
This is my first PC gun so what do I know.