Pentax MX Troubleshooting

The needle in the viewfinder doesn't respond when the meter switch is activated.

Install a new battery in the camera.

Check the contacts in the battery compartment. Old leaky batteries are a common problem and the acid can corrode battery contacts. Vinegar can be used to clean the corrosion. Isopropyl alcohol or a contact cleaner can be used to clean oxidation.

The LEDs in the viewfinder turn on but don't turn off when the advance lever is pushed in.

The reflex mirror in the body of the camera is stuck up in the taking position blocking the viewfinder. The shutter won't fire and the advance lever is locked.

When the shutter completes the exposure the closing curtain trips a latch, which releases the mirror and lets it return to the viewing position. If the mirror return latch is dirty, it may not be releasing properly.

It's also possible that the closing curtain is not traveling fast enough or with enough force to trip the mirror return latch. Getting the curtain back to a proper operating speed requires a more thorough shutter service.

The shutter won't fire and the advance lever is stuck. It won't do anything.

The number on the frame counter doesn't increment when the film door is closed and the camera is wound.

The frame counter doesn't return to zero when the film door is opened.

A hot-shoe mounted flash will not fire when the shutter is fired.