HELP! - Very little info on clusters in this time period.

I've done the newer style (an 88) gear replacement. So please, It's not that type.

Looking for advice on 75-80 style clusters

Last time I drove this car (almost a year) I removed the cluster to fix the odometer/Tripometer. Occasionally they would 'kick-in' and function for like a mile or two tops. Otherwise, they wouldn't move. Speedo worked fine (I think).

Cluster is out and I have two replacement/part clusters but I prefer to fix my original not swap.
Speedo/Odom/tripom unit is out of cluster. You can spin the hose connection with a small square drill bit and it spins one of the gears but does not turn the mile numbers. I'm pretty sure one of about four gears are bad (maybe more) or loose.
I have donor clusters but on the 75-80 style you must remove the face and first the needle. None of the visible gears are missing teeth or cracked looking.

I broke the needle on one donor and don't want to do it again on the good one.
I will upload pics later. Does anyone know this time period of clusters well?

Thanks