Porta One will not record

[galaxya6]

I have Tascam Porta One that will play back and mix yet will not record on any channels. I have dabbled a little in the past with the older analogue electronics and would appreciate if any one had a circuit diagram of the unit that could be emailed or faxed.

The record LED does not come on when the tape recorder is set to record, it maybe a common fault so any ideas would help.

I have no manual for the unit, have tried all combinations to record based on the later Tascam models, maybe I'm doing something daft ??