[FrankJ]

If the total parts were less than 120 lb, & presented for inspection, they could switch back & forth to their heart's content without reinspection. That is fairly clear in the rules.

There is nothing in the rules saying you cannot continue to modify the robot with parts in total would exceed 120lbs. If your parts were in the R-21 30lb of spare part allotment you could re-use them with re-inspection. If not rule R21 would come into play & you would have to fab new mechanisms using raw material & cots parts. (shooter included.) The way your LRI interprets all this of course will be the final decision. All else is speculation.

If they presented & passed inspection the robot each time, they are legal by definition regardless of how others interpret the rules.