This is pretty easy. Most clocks fail because the points (yes, paints!) inside weld together. Simply open up the clock, find the points, seperate them if necessary and carefully dress them with a fine fine. Put it all back together and watch the time fly!
The clock can be removed by removing either the dash pad or the glove box assembly.Also lubricate the points where the wheel with the hair spring is .They often are dry after 30 years and as well clean up the points that are the electric contacts for the tensioning wheel
I am working on my 3rd Cougar - 69, 68, 69 - and I constantly run into things that I have never done before. It's great having a bunch of Cougar guys to swap notes, stories and ideas with. It's not easy living in a bowtie world!