my 1950 mercury: the hydraulics don't work for the convertible top, power windows and seat where to start
Check the fuselinks at the starter solenoid, then the fuses at the fuse box, if those check good them test for power and ground at the switch, then through the switch, if those all test good then test the wiring from the switch to the relays, then the relays themselves, then the wiring to the hydro motor, if all that checks good then the hydro motor is bad. Most problems with those I ran into back in the day were relay related, but age can cause other things to brake down like wiring and switches.
Drivers side up under dash on the firewall, you might need a flashlight to see it.
Looking for a Used Monterey in your area?
CarGurus has 1 nationwide Monterey listings and the tools to find you a great deal.
Search Mercury Monterey Questions
Mercury Monterey Experts