Re: johnson 1980 tilt/trim clicking
Low battery, or as fishfeatures mentioned, possibly the solenoid. If your PTT unit is the original with a 3 wire motor, you only have 1 solenoid. You said that there is no sound when DOWN is hit. Not sure if you meant no clicking, or nothing, as in the trim motor doesn't operate. If the problem is your solenoid, the DOWN operation will not be affected. Start by jumping the terminals on the solenoid.
This diagram may help:
