Mitsumi CR-4801TE controls



I own a Mitsumi CR-4801TE. Lately I had been having troubles burning discs, the error message was “Medium Error: Write Error”, no matter what media was.

I opened the drive and found inside 5 rotational controls. I manipulated the fourth control and the recorder now works fine.

My question is, what did I change? And how do I know if it is set up to an optimun value?

What are the controls for?