Some other bits to check - see if the lens is seated correctly, and the contacts on lens and mount are clean. (Ok, so there are no contacts
) Try a different, known good, lens. When you change aperture, is there more resistance in one direction or another (ie. the camera lens sensing mechanism is sticky)...
On my KX, opening up the lens is harder than closing it down. Also, the meter once became intermittent when I was using the 43ltd, but works fine with the M50/1.7. I think these symptoms are related: something mechanical isn't moving as freely as it could, in the camera.
If it isn't mechanical, then I'm suspicious of a capacitor or resistor or poteniometer having gone bad in the circuit.