DG; problem with adjusting knob

i have a sigma-tek vacuum driven DG. the adjusting knob which is used to reset the gyro to the magnetic comass is not engaging the compass card anymore. has anyone any experience with taking this thing apart? what kind of connection is in the unit? would like to save this unit as it is otherwise still working fine. [steam gage pilot].

Try loosening the set screw on the knob and sliding the knob out just a tad. I found that with the Nulites on the DG I needed to do that or it would not engage.

Roberta