The bad is, you loose some time and money, and still have to have it rebuilt, the good, it turns out good and you do more and show some one else how to do it!
I have shown several people how to rebuild t350's, I tell each one to show some one else how to do it. It is not hard, you just need to think (follow a manual) and keep it clean, no lint!
I didn't have a manual the 1st time I did one (I had text, no pic's), and no one to help, and it turned out right, that was the '70's, I have done many different makes since.
Go for it!

My .02 worth!

Pat