Mamiya 6 shutter glitch

I have been using my M6 for a number of years without problems. I get the whole kit tested by a mamiya technician fairly regularly as a free service from one of the local photography exhibitions in MN. Anyway, the problem started earlier this winter, and I attributed it to potentially cold batteries, and it went away when the batteries were warmed up in my pocket for a while. Unfortunately, yesterday, the problem came back. The batteries aren't brand new, but are not old, or out of juice either.

When pressing the shutter, the shutter opens, and appears to stay open. I quickly put on the lens cap during this time, and stopped the lens down to avoid anymore fogging than the one frame. I powered off the camera, and removed batteries, and put them back in. Switched it back on and the meter appeareed to work, but I could not wind it on as the shutter was still open!!
Eventually, the shutter closed, and I was able to wind it on and close the film blind. I swapped lenses and then the camera worked as normal afterwards. I swapped back to my original lens, and again things were back to normal Could this be a battery problem, or is there something else going on that I need to be aware of? Could there be a bad contact somewhere? I can remember in the cold MN winters when temps got down to -15 both my 75mm, and 50mm lenses shutters did this.

Try cleaning the lens and body electrical contacts. It could also mean that the shutter needs a clean, but I would assume an electrical problem first.

grahamp, Actually I think I have found the problem, and it is the batteries even though they are not out of juice. I downloaded the pdf file from Mamiya, and they mention a scenario where the shutter can stick as the batteries deplete. There is a tiny button on the side of grip (looks like a digital watch reset button) that you can push that will make the shutter fire and close. I reset this button, and changed the batteries. I dry fired the camera with the back open and the viewfinder display is brighter. The PDF file really explains things well.