How to troubleshoot a malfunctioning gearbox in an Audi 80?

I recently noticed that my Audi 80's gearbox is making strange noises and seems to be functioning poorly. I'm not sure what the issue could be and would appreciate some guidance on how to troubleshoot and possibly fix it myself.

If you're experiencing grinding or whining sounds while shifting gears, it could be a sign of low transmission fluid. Check and top off the fluid level to see if that resolves the issue.

In some cases, a faulty shift solenoid can cause a malfunctioning gearbox. It's important to have a professional diagnose and replace the faulty solenoid to prevent further damage to your gearbox.

Another potential culprit for a malfunctioning gearbox is worn out bearings. If you hear rumbling or roaring noises while driving, it's best to have a mechanic inspect and replace any damaged bearings.