I don't believe the K1000 had a user interchangeable focus screen. To remove the screen you would pretty much have to disassemble the entire top of the camera and this is not recommended unless you are a very good do-it-yourselfer. And I mean VERY, VERY good!!!!!! In other words, don't do it. Probably the best thing to do if you absolutely must have a different screen in the KX is to check with
Eric to inquire if he has one and what it would cost to install it during a CLA. After all, if he has to take it apart, you might as well have him clean, lube and adjust the KX along with new light seals so the camera will be good for another 30 years.
CW