Hmmm.... The ones on BOTH of my Novakons ARE the check-valve type, a mix of #2s and #3s. Of course, I have since removed them all, and setup a system with needle valves so I can control distribution. When I get some time, I'm going to setup a system that uses a pneumatic positive displacement pump and valving to automatically pump oil into each circuit individually on a programmable schedule, based on actual machine run-time.
Regards,
Ray L.