| MM-1100 | Addition of 1-inch tape tension adjustment control | Open album: Addition of 1-inch tape tension adjustment control |
| MM-1200 | MDA upgrade kit, parts list and instructions | Open album: MDA upgrade kit, parts list and instructions |
| MM-1200 | PURC schematic drawing error correction | Open album: PURC schematic drawing error correction |
| MM-1200 / MM-1100 | Search mode not cancelled by end-of-tape function | Open album: Search mode not cancelled by end-of-tape function |
| MM-1200 | Bias leakage | Open album: Bias leakage |
| MM-1200 | Modification to improve Dolby operation when PURC card is installed | Open album: Modification to improve Dolby operation when PURC card is installed |
| MM-1200 | Reel motor drive amplifier improvement | Open album: Reel motor drive amplifier improvement |
| MM-1200 | Resistor failure in power supply | Open album: Resistor failure in power supply |
| MM-1200 | Takeup tension controller update, Nov 1982 | Open album: Takeup tension controller update, Nov 1982 |
| MM-1200 | MDA stability improvement | Open album: MDA stability improvement |
| MM-1200 | Dolby interface modification | Open album: Dolby interface modification |
| MM-1200 | Transport control PWA | Open album: Transport control PWA |
| MM-1200 | Search to cue multiplex beat | Open album: Search to cue multiplex beat |
| MM-1100 | Control box miswire | Open album: Control box miswire |
| MM-1200 | Reduction of servo tone | Open album: Reduction of servo tone |
| MM-1200 | Last MDA revision schematic | Open album: Last MDA revision schematic |
| MM-1200 | Audible noise from reel motors | Open album: Audible noise from reel motors |