U302 with 1610 Loader Hydraulic HELP!

[Vermont_MM]

Hello Everyone,
Finishing up mechanicals on a 1970 MM U302 Super Diesel (sn:140) with a 1610 Loader.
The loader uses the Tele Flow Remotes.
The lift Cylinders will occasionally freeze. I can hear the pump load up, but no lift. Lift cylinders operating on the inner lever.
I can usually convince it to shake loose however it's rather annoying and happens at random without me provoking it.
Are these cylinders check valved? I didn't think so but without tearing into them, I'm not sure. Are the internal to Cylinder? Cylinders appear to be correct for teh 1610 but no way to tell for sure. I will post the SN: of loader later today if it matters. Any insight would be appreciated. It acts as though there are check valves working in conflict with the Tele-Flow.
There are QD's in line, I can break them normally with loader frozen. Cylinders are straight and good otherwise it's a hydraulic issue, not mechanical.

School me, not a lot of knowledge base here to work with in Vermont.
Kind Regards,