Shutter Delay Issue on Mamiya RZ67 Pro II

Hello,
I am new to film/medium format, and have recently picked up an RZ67 Pro II in excellent condition.
However, I have immediately come into a shutter issue that could do with some advice and experience.

When left for more than 12 hours~ (day to day) the first and only shot, with or without film, has two very distinct sounds with around 1 second delay (assuming this is the mirror up and then the shutter), despite the camera being set at a faster shutter speed. After this first delayed shot, it then fires correctly to ear at all different shutter speeds.

Sadly this is frustrating as I have wasted many first shots to this delay. I am first going to replace the battery and hopefully that may help, but has anyone ever experienced this before or could advise.

Cheers!

Yeah, I've been shooting RZ67 II cameras for 20 years. Maybe it's just a drained battery. When you shoot on slow speeds you can hear the shutter close after the mirror flops up. But at 30th or higher the shutter closing is not apparent.

Could be the lens shutter needs work. Try a couple different lenses. They all have electronic shutters so if the shutter is hanging up, it's probably time to consult a professional.

The other thing that comes to mind is make sure all the body to lens electrical contacts are clean.

Thanks guys, will try the other lens to check. I have the 110 f2.8 and 50 f4.5 I look forward to shooting with!
I have taken it recently to a film specialist who confirmed all the contacts are clean between body and lens. He recommended the battery swap, and failing that, it may be a deeper issue in the circuit board?.. Hopefully not.