After receiving the manual, make sure after the first solder connection is made, to check and confirm everything is working for that particular connection.
I bought a MR-4 new from these idiots in the early 80's.
The manual showed the wiring diagrams for the console / internal patch bays.
We hired two TECHs to wire the console to everything in our room.
Took about three days.
When we went to test the connections, we found they did not work.
After some testing and a few days of calls to Harrison, they asked us what number manual did we have. Once we told them the revision of the manual, they said,
OH YEAH, that revision has incorrect wiring diagrams in it.
About a week of wasted time, and thousands of dollars later...we got it to work...
But then the real fun happened.......