As Grand73am mentioned, this design has been around a long time. The clock in my 70 442 is the same.
People have asked if the clock can be adjusted and, if so, how. Here's a couple pics. One from my 70 442 owners manual and one from the 78 pontiac chassis service manual. It's funny, the info regarding the TA is literally the next paragraph after what ta78w72 posted regarding the disclaimer.
If I were to go to all the trouble to take mine apart to service it, I would hose it down with an electrical contact cleaner or at the very least plain alcohol. Something to break down the old gummy oil and dust that is in the bearings/moving parts. Then oil is with a light machine oil like 3in1. That said, I did this on my 442 and it worked for maybe a few weeks.
Some have mentioned the quartz conversion. I know they are available for the 68-72 Cutlass, Lemans, Chevelle etc so I would think there is a kit for the 78's too. The quartz 79 TA clock sounds like a great idea. Anybody personally done that?