What is the best way to identify if my Audi 80's transmission needs replacing?

I have been experiencing some issues with my Audi 80, particularly with shifting gears. How can I accurately determine if I need to replace the transmission?

First, check for any warning lights on your dashboard. If there are no lights, pay attention to any unusual noises or vibrations while driving. It might also be helpful to have a professional mechanic do a diagnostic check.