I'm working with the 'project' Scully 4-track. It sounds great, record and playback align fairly well, and runs relatively steadily. One minor caveat, the damn thing doesn't erase by more than 10 dB. I'm using 456 and not hitting tape too hard. I'm unsure if the problem is as simple as adjusting the erase pot or if it's as involved as needing new erase heads. I'm afraid to adjust the erase bias pot just yet because I don't want to send to much current to the heads and wreck them if they aren't already wrecked. The manual has no information on adjusting the erase bias either, I'm imagining it's the same as an Otari or Studer 2" but I'm not too sure.

Any ideas?