Husqvarna forward drive problem

I have a husqvarna cth140 twin ride on, hydrostatic drive.

I reversed to empty it recently and when I put it in to forward it only creeped out. Still driving slow and takes awhile to build power up. Engine is fine but I seems as if the power is not being transferred to the wheels.

Didn't hit anything while reversing, but someone told me it might be a sensor.

I have noticed while cleaning it it take a while to get speed up while wet, so I'm wondering did I hit, dirty a sensor?

Anyone ever come across something like this?