We have a 1987 model Tappan dishwasher, but I'm worried about its condition. The detergent dispenser cups won't open sometimes when you run it,(it has a sideways-mounted, motor-pump assembly, non-reversing, with a pump valve flapper, which has been known to stick open, and it sometimes drains out, when it is supposed to shoot water and wash)and the control panel is loose, it moves each time you open and close the door, as two screws that hold the control panel are missing-the timer once had a loose wire that we had to fix. Any maintenance tips for this 18-year-old Tappan dishwasher? How much more life can we squeeze out of it?