Rivet gun problem

[Eric Brown]

I've got a Cleveland 4X rivet gun. Lately, the gun will not perform when facing downward. It will just "buzz" or "hiss". When placed horizontally or facing upward, it works just fine. I disassembled it and did not find any obvious problems. I did a little cleaning and lubing with tool oil and reassembled. Same problems. Supply air pressure is 100-120 psi. I purchased this gun used from The Yard 4 years ago. It had been working fine up until a few months ago. Any Thoughts ???

[CraigCantwell]

I know it's a strange question, but do you have a set in it and fully inserted when it won't function?

[Eric Brown]

I know it's a strange question, but do you have a set in it and fully inserted when it won't function?

Yes, I do. Have tried several different sets. Same results.

[Eric Brown]

I know it's a strange question, but do you have a set in it and fully inserted when it won't function?

Later that same day................ I may have found a solution, myself. I added a week spring to the front of the piston to assist it in its "blow back" travel after hitting the rivet set. The gun is now working 90% of the time.