I bought 3 faulty matrix 1000s about 4 years ago for around £680 in the UK, two dead and one alive but poor sounds. I had no experience of the M1000 but after finding the schematics and probing around I replaced some bad logic, batteries, V2.00 firmware, volume controls and voice chips and all 3 were working. But one had the transformer buzz that happens when they get old.
I found an article on installing a meanwell RQ50C as a replacement for the old transformer and power section. Unfortunately the regulators and diodes are on the main board so you need to remove the regulators and tap input the outputs of these.
Here are some of the photos I took of the removal and installation. I did it on all 3 units to future proof them.
