Most likely it can be repaired or at least improved
The calculator is screwed together, two screws under the label which is difficult to remove without damaging, recommend heating with a hairdrier and very carefully raising the top corners until the two screws are revealed.
Once inside you need to unscrew the back plate that supports the circuitry and motor. There are six screws holding this assembly down. Be very careful with the circuit board with respect to static, but it removes easily.
The keyboard contacts are metal sheets that deflect to produce the contact and desired key feel. To correct your issue you need to clean underneath these contacts with either rubbing alcohol to remove any goo that may exist, and/or use a very fine (1000 grit) sandpaper under this key assembly. A little sanding goes a long way and it is easy to permanently damage you unit by being too aggressive.
This is an excellent time to thouroughly clean your keys and plastic parts (not electrical parts) Diluted 409 or other cleaner works fine but make sure you completely dry the parts! Residual water will corrode without mercy!
Reassemble your cal and hopefully it works better.