If you own a 1985-88 Cougar with the optional equalizer (Premium Sound required), then you may have run across a common problem: the power button not staying locked in on the EQ. Over the years we've seen this time and time again, and probably the most common "solution" is to jam a toothpick next to the POWER button, cut it off, maybe dab the wood with a Sharpie, and there's your instant free fix. It's not professional, but it does seem to get the job done.
However, if you DO want a more professional fix, Shanon offers a solution:
"This repair allows for the use of the stock EQ but please note that once this has been done, it can no longer be turned off.
"If the power button on the EQ does not work, do the following:
1. Remove the EQ from the dash and take it inside or to a place where you can work and not lose parts. You will need a hot glue gun or silicone sealant, a soldering iron, flux, solder, needle nose pliers, standard pliers and various small screwdrivers and a little common sense and ability to solder (minimal experience is necessary, be sure to use the flux on all parts prior to soldering them or the solder will not work.)
2. Disassemble the case of the EQ carefully and take note of how it came apart. You will need to remove the face of the EQ as well. To do this pull on the slide covers until they pop off and remove the Balance knob. Remove the face of the EQ carefully and set all the parts aside. Next remove the nut around the balance knob and pull on the power and "EQ lights" buttons and set them aside. Remove the bottom black plastic cover. This should leave you wtih a piece of electronics equipment that looks very little like what you started with, but this is what must be done. Next, remove the screw on the left side top of the eq and push the side panel away from the body. Next, locate the two white push plugs that secure the top circuit panel to the bottom. After you have unfastened these, open the EQ like a clam shell.
3. Locate the bottom of the POWER switch. Heat the soldering iron and remove the switch by unsoldering the entire 8 pin unit from the circuit board. This takes some patience but it can be done by using a hot soldering iron on the back of the switch and constant pull on the front. Run the iron over the back connectors while pulling on the front. Do this multiple times and eventually you will get it. Next you will need to connect the holes that are left by soldering in between them in pairs of 2. Solder #1 hole to #2 hole, #3 hole to #4 hole and so on. Be sure NO solder gets between the pairs or it won't work. After this is finished, take the unit to the car and plug it in and make sure it works before reassembling it. If it does not work, check that your soldering job is clean and does not touch any other group. If it does work and it will if you did it right, gut the switch and glue it back up so that it looks right but doesn't work. Glue it back into the stock location once there is no metal left in it to short out the job. This will allow the EQ to have a stock appearance, though the switch won't work. Reassemble the unit very methodically until it looks correct and there are no parts left over. Reinstall the unit in the car and enjoy."