Christen Fuel Pump troubleshooting

Hello, folks. I'm fishing to see if anyone else here's had the same problem
I'm having.

I've got a Pitts S-1D with a Christen wobble fuel pump. The action on it
has gotten so stiff when priming that I fear it's close to locking up. It
still primes fine and the fuel pressure's good when the engine's running,
it's just the hand actuated side of it that's got me concerned.

Anyone else ever have this problem? Can these things be lubricated? Any
info greatly appreciated.

Cheers,
Shawn
Pitts S-1D G-BKVP