I won't touch the Eq pots and will try to do some more work on the Ferrographs during the weekend.
Just to update: Both machines playback very well and in regards to the Series 4 all it might benefit from is optimizing the bias for recording (perhaps set it to BASF LGS35 or an equivalent tape of the era. Also making sure that the break clear the spool carriers (which I think they fully do) to address the issue of the slow wind towards the end of the tape. I have cleaned the tape path but it did not make much of a difference.
The series 3 needs calibration for recording purposes as the recordings are coming out very bright so considering that the electronics needed a number of components changed, the biasing etc might be the issue.
Thanks again to all
