You probably don't need a new regulator. The problem is likely with the clutch in the regulator. The original grease in there dries up and renders the clutch non-functional.
You can do a search for posts I made about this a few years back. The clutch can be removed, cleaned, relubed, and reassembled for like new performance. It's not hard, but you must be careful with that big spring.
Like I said in those posts, it would be great if we could purchase just the clutch, or even the bushings in them that wear out. Repop regulators have a reputation for being flimsy compared to originals.
Sounds like the OP has manual windows - here is a pic of the window regulator:
I thought the pinion gear on the end of the crank shaft is in direct contact with the [partial] ring gear on the regulator arm (like earlier year Mustangs Im familiar with). The pinion shaft is supported by a bearing under the little cover that is riveted on. What is this 'clutch' you speak of?
I would think if the OPs regulator is 'slipping' allowing the window to drop a bit then the pinion and/or ring gear teeth are worn which allows 'backlash' (clearance) which allows the window to move (drop).
Okay. Engine Stop. ACA out of Detent. Mode Control, both Auto. Descent Engine Command Override, Off. Engine Arm, Off. 413 is in.
-Buzz Aldrin, Apollo 11 LMP
Actual first words from the surface of the moon
Early Fox: 5.0L HO SEFI conversion, 5-speed, 8.8 w/3.27:1 TL, full dual exhaust
1968 coupe - Ordered 12.15.67 Delivered 2.1.68: 8T01T, 65C, 289 conversion, hanger queen
Last edited by Paul1958; 05-03-2016 at 02:02 PM.