Are the parts interchangable? I have a blue model with a slightly askew column. (probably worn plus when the counterbalance had been released earlier for storage, the coils sprung out of the tube.) A black column I picked up at a junk store appears to be in much better shape. Can I simply remount the "projector assembly" (for lack of a better word) on the better column? If so, which way would be better, via the two bolts on the pivot or by pulling the retaining clips on the shaft?