After letting '66 FFR 88 sit much too long during brake and seal rebuild (excuse was pandemic, no garage heat, and disc surgery) I wanted to start the landy and test the brakes before I bolted the fenders back on.

I charged up the fairly new batteries (optimas), reconnected the terminals, turned the key, hit the ignition switch and nothing but a loud buzz from the solenoid (original - so 55 yrs old). Double checked batteries - about 12.9 V ea - cleaned all terminals and tried again - still a buzz but no starter engagement. Whacked solenoid with piece of wood. Things engaged briefly, but not a seond time. Still not getting juice to starter, I think. But not sure if solenoid is engaging fully.

So - what's my next step? Should I try to jump the two terminals on the solenoid to see if the starter engages? That would tell me if the solenoid is the culprit. If the solendoid was a cheap part, AND if I saw one that matched the look of the one I have, I'd just swap it out. Neither of those conditions apply. All the ones listed look like square boxes with spade terminals, mine is a round style with nuts holding down the control wires.
Has anyone replaced old style with newer varieties? Who made the originals? They look like AC/Delco 24V units.

Any advice or insights on next steps would be greatly appreciated.

Best

66 FFR registered as OLD TOY
Cape Cod