: But....... found out my pumps won't work.

: Any ideas on how to get 'em functioning again?

Yup- this happens.
Is the resin and hardener warm (ie 'runny')?
Is the resin still clear, or has it crystallized?
Check the pump spouts- sometimes dried 'crud' is plugging the opening. A piece of guitar string (E/A) can be handy for cleaning those.
I hate to waste epoxy (I'm cheap) but sometimes I've had to take the pump apart and clean with solvent. (Hot water works on the WEST hardener, as I recall; alcohol for resin). Pumping solvent through the pump can work sometimes. I don't know what pumps you are using, but my WEST pumps have a ball and spring arrangement, and it can get 'stuck'.

: Any details on measuring using weight rather than volume. Someone
: posted they used an inexpensive digital scale from Harbor
: Freight and got the weight per ounce from the manufacturer.
: (Easier to do if you don't discover the issue on Friday
: afternoon and live on the west coast.

I must be a slob- digital scale and epoxy mixing don't seem a natural combo for me.
For volume mixing, if you are using a standard mixing container (plastic cup or similar) , you can make a 'calibrated Popsicle stick' (mark with pencil or burn marks) using water and a measuring cup (or a syringe). Sit the stick in the cup and add resin/hardener to the marked lines.

: I think I have heard that the hardeners take on a tint but seem to
: do their job despite age. MAS says the resin has "an
: infinite shelf life"
WEST hardeners do get darker over time but work OK, in my experience. They will tint the epoxy, so keep that in mind.
Resin can require warming up to get it liquid again.

Happy building!