The movement has 77D with a F under it and a ST in a diamond with a circle around it and U.S.A. I have the weight and pendulum I just kept them out so I would not break the glass. When I look at the movement it looks like a black coil spring is broken on the bottom, I've tried to show it in the picture. Could anyone tell me what the part is called and is it hard to find and fix?
That your Seth Thomas wall clock has the 77 movement is strongly suggestive of REGULATOR No. 4. It was offered with either 80 or 72 beat pendulum, the 72 beat being slightly longer than the 80 beat pendulum.
The broken spring is the pendulum suspension spring. Replacements are readily available from clock parts suppliers at minimal cost and are easily replaced, being held in the split stud with a pin. It's a common part used in the ST #2, 4 and many similar clock movements that have a reasonably massive pendulum bob.
The "green goo or verdigis" on various parts of the movement reveals a nice clock movement in serious need of cleaning. The green crud is the result of "rancid" oil lubricant that has become acidic enough to combine with the copper component of the brass alloy giving the slime a green hue. Probably an oil containing vegetable or animal fats was blended with petroleum based lubricant to minimize spreading. Too, it is obvious that the oil spread where it isn't needed or desired. Only the pivots or ends of the shafts should have only a miniscule amount of lubricant and never on gear or pinion teeth.
Fortunately, the No. 77 similar time-only-weight driven simple movements are easy to clean and maintain by a qualified clock repairer.
Could you picture the bottom of the clock and also tell us the length?
Like Les, I am opting for a Seth Regulator #4 ......the one that is a bit longer with the 72 beat movement. This model would be 42" long.
It is a Seth Regulator #4. Tran Duy Ly's books indicates 1921. That is one of the catalogs where it was pictured. Your clock should beat 72 times per minute. The movement has a 36 tooth escape wheel. Nice clock.