Drum assy for SL-HF900

[columbia]

I acquired a fairly nice 900 a few weeks ago. It had a loading problem that I was able to take care of. But the drum assembly was physically locked up. I was able to fix that only to find that the video heads themselves are shot. I would like to just replace the entire video drum assembly with heads. Does anyone know where I might find one or can I use any SuperBeta Hi-Fi head assembly? Thanks much in advance..dan