Hmm, makes me wonder what I'm doing wrong! Yes it's geared when you engage turbo, the pad is driven.There must be a problem with your sander as I have the 125mm version and I find the turbo mode is a beast.
From what I understand it’s a geared sander same as the Rotex.
How low do you go on grits? I don't think I've tried less than 60g.
36 or 24 if available might help.
Also how much pressure should you put in a sander in general? I put a bit of weight on it but I could maybe go a bit harder.