I’m away from home at the moment and so can’t look up the part number for the VOR block. On my Cardinal it was under $20, but Mark Van Wyck said the part for the 150 cost $200.
Until I get back, here are the details on how to charge it. It’s from my Cardinal but the 150 follows the same steps:
https://www.cessna150152.com/forum/...e-cardinal-rg-engine-r-r.html#Post437693