I know the UK Escorts have a lot of differences, but I suspect the wiper motors are fairly similar.
It could be the wiper arm is loose on the pivot. Good luck in unscrewing the nut and prying the arm up from the pivot. It should have a knurled surface on the pivot, to mate with the inside of the wiper arm. If the inside of that wiper arm is worn away - a new arm is about the only good repair.
When the front wipers act up:
I have found the grease inside the gear case that is at the end of the motor to be a problem. It gets hardened to the consistency of old chewing gum, and prevents the little contact fingers from touching the metal patterned areas on the face of the gear. Cleaning off the old grease and putting down new grease solved that. I have 3 Escorts and have needed to do this to two of them. I took the wiper motor out to do it, but for the 3rd one I might try doing it on the car. Its possible to pry the plastic cover off after removing a couple of tabs and perhaps a small screw.
I havent seen this on Escorts, but on my Dodge compact car (Omni) the pivots/links that are under the cowling (or fascia?) came loose - from old age; and the arm stopped working.
Most anything that goes wrong with one of my Escorts gives me the opportunity to do a pre-emptive repair on the other two. I much prefer fixing my car while parked in the driveway: Compared with having to try getting it home from the highway on a rainy day without wipers or paying the fee for a tow truck.
You know about the UK based Escort forums? Two of them are:
www.feoc-uk.com and
www.fordescortclub.co.uk
