You will probably get some suggestions, but in the meantime go online to check out Moyer Marine (www.moyermarine.com). Don is an excellent source of parts, advice, rebuilt engines etc. He has a rebuild maunal that should be helpful.

There are transmission adjustments that you can find some instructions for on the web (including Moyer Marine) but it sounds like your problem is more severe. Still knowing what to adjust could help locate the problem.