Pentax meter problem spots 

probably the meter cell in the viewfinder got thrown out of whack. you can get to by taking off the top and removing the prism but its a lot of fine work and the needle is as delicate as a human hair. The cell is replaceable if you could ever find one.

@@tobroken1965 thank you 👌👌

Don't drop them...

@@mikepxg6406 Don't drop or smack them hard.

sorry, no, i got rid of a lot of stuff.

@@tobroken1965 Well, thanks anyway. Thanks for the videos, they really help!

I have used a variety of methods, all with mixed results. In most cases, like the spotmatic above with its nylon battery well (this fits the new style 387s battery @ 1.55v), I generally start with vinegar and a Q-tip or even a tooth brush, ( would also do this with the bottom removed). If that doesnt quite do it then brass or other metal polish and a Q-tip. If the corrosion is crusty, a soak in vinegar can be helpful, followed by very a very gental toothbrush scrubbing. In cases when there is pitting of the metal surfaces, you can try streching a narrow piece on fine emery cloth (400 or similar) over the eraser end of a pencil and lightly scrub the affected areas. On the compression contacts inside the camera body I try to stick with gentler methods like metal polish. I have used similar methods on the newer style cameras that take the more modern batteries like the 357. Good luck, if you find another method or try one of the above methods, please post your results, every little bit of input helps.