Remember that there is a restricted range of line entry angle for winches i.e. the fairlead. See if you can find the mounting instructions for your model. You can normally find that kind of thing by google searching "winch model" installation or instruction. Anyway, if not then look at other winch brands of the same size and see their recommendations. In most cases this entry angle is primarily to help prevent over rides, but it may possibly affect your stripper arm problem too.
Unless the arm is actually broken, I can't imagine why you're having such a problem. Do you have a photo to share? Have you changed your brand, type or size of sheets recently? Has it always behaved I this manner or is the problem recent? What would have changed? Okay... good luck. Don't spend a fortune here, save your money for the yearly 2 for 1 Lewmar promotion at West Marine.