Panasonic PV-1231 idler trouble

[xargos]

I recently acquired a classic Panasonic VCR, the PV-1231 (photos of one here, not mine) from 1984. After cleaning the heads I fired it up and found that the only issue with it was that it couldn't properly rewind. Since there were no major problems, I bought a rubber replacement kit from Studio Sound Electronics (MBK-07) that also included the idler arm (which they don't seem to have any more).

Last night, I decided to take the VCR apart and install the kit. I had no issue with the belts or the pinch roller, but the idler arm is a different story. Since putting in the new idler arm the VCR doesn't work properly. The arm doesn't seem to want to swing to either the supply or take-up reel, thus preventing any operation. Has anyone seen this before? And if so, what might cause this?

Thanks.