I have a pair of these that I took apart and replaced the grease after the blades hung-up on the crank shaft. The gasket that goes between the housing and cover ripped and so I cut a new gasket myself. The only problem was that the gasket material seems a little thicker and now the blades will hang up on the crank shaft whenever I start trimming. Everything looks good inside. I'm stumped on this. Bad blades maybe?? Any advice would be greatly appreciated.