Mamiya RB67 Pro S Mirror Stuck

Starting a new thread to continue on from my Pentax post.

A quick recap. I got rid of the Pentax 67 because it looked like the electronics were fried, and went fully mechanical with an RB67 Pro S. The mirror is stuck halfway up. I am able to push it down to get the lens off, but it won’t stay down. I can’t fire the shutter and the cocking lever is forward with very little play. I have downloaded the service manual and know how to get to the mechanism on the left side of the camera, just wondering if anyone has any easy suggestions before I head down this rabbit hole.

I have a (newer 1990's) motor Hasselblad, this was happening. I put a couple drops of Kodak movie film cleaner, solvent, on the gears. Works fine now. Didn’t open it up. Applied it from outside, very sparingly.

Make sure the Mirror lock-up setting on the lens/shutter isn't engaged.
Are you sure the shutter in the lens is cocked?
The various interlocks are important!