Keys work stiffly. With a toothbrush., loosen eraser crumbs in the key slots. Then blow out crumbs and dust with a vacuum cleaner hose. Run a very little sewing machine oil into key slots and work keys.
Carriage moves sluggishly. Put a drop of light oil on either end of the rod or bar on which carriage glides, Work carriage back and forth.
Letter head on key hose. You can fix this temporarily by raising key half way and supporting it there. With a small pair of pliers, carefully position head. Be careful not to mar the letters. Hold with pliers and heat one side of head with soldering iron briefly. Remove heat but not pliers and let solder harden.
Key sticks at ribbon slot. Check on wnich side of slot key is binding; then bend key head slightly to other side. Often if you just wiggle key back and forth several times it will straighten out.