Apparently no good deed goes unpunished. I elected to clean and re-grease the winches since I had no idea when the PO had done so. At the first sail after the cleaning, both winches began to slip back after winching in the jib sheets. I was even to do replicate the problem when they weren't even under a load. I opened and rechecked the assembly and everything appears in order. The one thing I did not do was replace the pawl springs with new ones since the existing ones appeared OK. Is it possible that the springs are the problem? I've purchased replacements but haven't had a chance to install them but wondering if that's even going to affect a change.