Hi,
I am fairly new to autosticks, but I have had to repair mine so I am somewhat familiar with its operation.
Is there any rpm change when trying to change gears?
can you hear the vacum valve clicking?
If the answer is no ...
the fact that it is grinding tells me that the clutch servo isnt engaging, try to see if the shifter switch contact/wire is working properly and sending the "engage" signal to the vacum valve. pull back the boot at the base of the shifter and check that the grey wire coming out of the base of the shifter is intact and grounds out when moving the shifter. I was able to test he rest of the system by grounding this wire and engaging the clutch this way, thus verifying that this was the problem on my autostick.
If thats working I would then verify that the vacum valve is actually sending vacum to the servo, again you can test the valve by powering up the solenoid and listening for a click and rpm change (doing this creates a temporary vacum leak), then check the servo its self for vacum leaks or ripped diaphram.
another problem could be the switch on the tranmission the disables the vacum switch when the shifter is not in neutral, but I would check the other components first.
more autostick info here:
http://www.vwar.org/
I hope that helps
Bry