The door open and close relays on those old Dovers are in back of the swing panels. They are potter brumfield relays. check those contacts. Also the capacitors around the contacts.
WCR is what we call that controller. SE is not just the Safety edge in these, it’s actually your open pilot and has to pick to open the doors. It can be picked by the edge, door open button, fire service, & CS picks SE when a call is answered. Do you have a set of prints to see what’s picking SE?
This may not be relevant but worth mentioning when talking about going through IBM relays with a tester. This bit me bad a couple years ago on a WCR controller. I clean them with the little burnishing sticks from Adams, re-pin and replace as necessary. The newer IBM relay testers that Sees and, I think, Adams sells don’t have a set of LEDs for the N/O and another set for N/C. They use a single bi-color LED that goes green for N/O and red for N/C so they work fine to tell you if the contact is closed or not when it’s supposed to be. But they will not tell you if a contact is closed when it’s not supposed to be so if you get a set of pins crossed up like I did, the relay can test good even though the contact never open.
What type of operator? Just saying, I found bad diodes, 1 shorted, 1 open, on a DC68 mark II. Doors would hang open, even with SE out. Diodes not on print. Print in DO not legible. Removed the shorted 1 and doors worked great. I had a lot, and I mean a lot, of energy wasted on this one. It helps to know OLD guys.
I know you said the edge was good, but.... Symptoms you describe sound like the detector edge cable is opening up internally. Pinched on the car door header, or the cable may be chaffed through on a metallic fastener on the door itself. Or, an intermittent weak TX or RX edge. Do you see the colored LED fire on the door edges when you get a reopen?
Does this job have a safety edge also? If so, then I would say your safety edge is retracting too far at final close and at full open and actually triggering the micro switch. Also remember wiring on Oildraulic and or older dover control the photo eye should drive the EE input and the safety edge the SE input.