Drill gearbox clutch
 

Any suggestions on how to lock the clutch on this year's drill motor gearbox?

Why?
 

We've never had to lock the clutch, once you set it into Drill Mode, it's very hard to knock is out from normal operation.

We went through all of last year's bashing and the clutch never gave us a problem.

I don't think you'll need to worry about it

There is another thread on this subject.

We are using a premium cable tie (ie cable ties with metal teeth from Home Depot or McMaster Carr) to lock our drill motor in gear.

There is also a method of locking the drill tranny into high gear by machining a steel (or HDPE) ring that fits inside of the transmission itself. If machining capabilities are available, this can prove to be a very effective method.