Mamiya 645 1000S shutter problem

I was doing a couple exposures at 1/4 second and the last one sounded like it didn't complete. At this point things are jammed up. The shutter will not work and the film advance will not crank. I did replace the battery so that is not the issue. I tried the mirror up and and the multiple exposure levers and still no joy.

And ideas or, who does reputable work/repair on this model?

Vince in Billings, MT

Maybe.......It's a fabric focal plane shutter so remove the film insert and carefully move* the closing curtain to the cocked
position and let it snap to the released position. Sometimes this type of shutter(in a 35) won't travel quite fast enough
at slow speeds to release the mirror. Usually the camera needs a cleaning.

*use a fingernail, nothing pointy.