[Jeffrafa]

From what is shown in the photo, I would guess that you are getting a LOT of slip between the wheels and the disc - those wheels are pretty firm, and you only have a single squeeze point for contact in a linear shooter. What other types of wheels have you tried?

Part of why the Ri3D shooter used pneumatic tires is because they can compress a lot and significantly increase the contact time for a linear shooter. As has been discovered by many now, those particular AndyMark pneumatic tires have weaknesses for high speed use, but the principle of a more forgiving tire and greater compression for a longer contact is sound.

Does anyone on the team have a camera with a high speed video mode so you can try and see what is happening? (many newer point and shoots have low res, high speed video modes)

I am not terribly familiar with the Modulox gearbox system, but based on the small gear I can see on the CIM, and the larger gear mated to it I think you have a gear reduction set up, is that correct? You can check by slowly turning the output wheel by hand and counting the revolutions of the motor shaft - if the motor spins more than once for one turn of the output, then you have a gear reduction.

Our team always likes to start prototyping shooters by directly connecting a CIM to a wheel, since it keeps things simple (too much squeeze can be rough on the motor bearings though). There has also been some talk online this year about teams wanting to gear up their CIM to make the wheel spin faster (as Ri3D did).

Some suggestions to test: higher grip wheels, more compliant wheels, greater squeeze/compression (to a point), and start with 1:1 off the CIM to keep things simple.