Sonic Shifter pinion gears fall off when shifting

[Trish Fisher]

Pinion gears keep falling off each time the motors is shifted.

The retaining rings are on all four of the pinion gears on the motor shafts.

This is happening on our practice bot, but it wasn't happening on our competition bot before we put it in the bag.

http://www.andymark.com/ProductDetai...de=AM-2509_118

Tomorrow at our meeting the students will:
1. make sure motors are tightened in gear box
2. make sure gear boxes are tightened together
3. fix bearings in center wheel
4. check rest of bearings
5. put gears back on with collars
6. possibly add more lube

Does anyone have additional ideas?

[Chris is me]

By falling off, I assume you mean the gear is leaving the shaft? With two retaining rings and a properly sized key, this certainly should not be an issue. An 8mm collar or two, while overkill, would do the job here if your retaining rings are not working.

[mikemat]

Are the cim output shafts on your practice bot shortened?