I got this Paslode F350S framing nailer for free because it's not working. The sleeve was gritty feeling and then I accidentally ruined it while cleaning. The sleeve seal was cracked and brittle and the post bumper was destroyed. I replaced all Orings, just to be on the safe side. See the links below for the parts and tools I used:
O-Ring Kit & Sleeve Seal (402011):
Post Bumper (500453):
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