John,

I'm mainly adding my 2 cents worth because I want an email notice to find out what happens here. I vote for the Rx vibration problem so swap out the xtal and then the whole Rx to see if that fixes it. If you want to add a nylon clevis on the motor throttle arm connection and you don't have room between the throttle and the firewall, you can have the pushrod go past the throttle and put a "U" bend in it so it comes back and connects to the throttle arm (hope this explanation is understandable.)

Joel