Thanks, TJames for your reply. Yes, opened and replaced a number of darlingtons in circuit around RL101. No VU’s on recorded tape. No change on micro pin 36 !REC.
Sorry for delay in answering, Martin! Thanks for the leads.
Checked all voltages including 14a around Dolby board. All present. But worst possible result for fault – after reassembly it works perfectly!! Tested now with many tapes both in playback and record.
Guess I just wait for something to show up some day … sigh