Initial inspection - Takeup spindle not turning in play mode, causing tape to slacken after capstan/pinch roller with auto stop engaging after some time. Fast forward operating as normal. Impossible to test play/record functions. Dolby NR light not working.
First disassembly - Idler wheel belts for tape counter and left spindle deformed; replaced with near equivalents. Capstan belt in good condition. Play mode right spindle idler wheel assembly hardened by grease; disassembled, cleaned and regreased. On reassembly mute switch leaf spring lost; swapped with Type I/II leaf switch and Type I/II switching hard-wired to Type I. The pause button assembly is difficult to re-link. Ensure that it is unlinked before taking out the transport and re-link using the spring play on the latching plate aseembly. Ensure that the smallest hole on the link is placed on the solenoid assembly, not the latching plate.
Second inspection - Transport working normally, play mode audio tests normal. Record mode testing indicates faulty bias - either no bias at all or off the scale when turning the bias adjustment potentiometer. Poor quality recordings.
Second disassembly - Ensured hard-wired Type I/II wires made good connection - bias issue remained. Removal of front panel revealed that the 1k centre-detent bias adjustment potentiometer had snapped along the PCB. Repair to original attempted but unsuccessful - replaced with standard non-detent 1k potentiometer. All potentiometers cleaned internally with contact spray.
Third inspection - Bias adjustment now works and good recordings made. Pause button sticks occasionally, either due to front panel clearance issues or bad grease. After a long tape reverse, the transport made a pinging sound and the capstan stopped in place. Transport does not function except in reverse.
Third disassembly - Fast-forward idler wheel assembly had cracked along the plastic keeping the idler wheel in place, with the wheel and axle found on the chassis floor below the transport. Axle and wheel reattached and plastic glued together with epoxy resin. Additional signs of cracking to other axle on assembly patched with epoxy, and allowed to dry for approx. 12 hours before reassembly. Motor and capstan lubricated with light machine oil. Capstan retaining nylon nut readjusted according to service manual specifications. Pause assembly regreased and relinked.
Fourth inspection - Only fault remaining is burnt out Dolby NR indicator light. Replacement ordered.