A guy on my other forum has 535 with a broken spring. He wanted to know how to replace it. I assumed it was like my 835 and had a screw cap. But he is saying it won't budge loose.... Any suggestions ? I showed em the 590 disassembly video and a schematic picture of the 535/590/835 series pumps. I suggested using a rubber floppy thing to open cans with, and the heatgun, wd40, breakfree and it's still stuck. It’s a camo finish so he doesn’t want to ruin it with a torch..... I think he's at the last resort....bring it to a gunsmith.... Am I correct in assuming it has a cap that unscrews? Or am I wrong?