normal reopen when at the floor, via call buttons, means you should get a reopen via the selector lz brush and contact.
you would also look at the dz contacts but if the front door has no problem then all this should be ok.(check for differences between front and rear actuation ie lzrear etc.)
as for the opening then stopping where are you measuring the 35v? at the motor?where is the lamda relay(assuming sgr)contact situated for the open relay?is there a rear open door relay? are the contact flexs ok?let us know mate how you go.
Sorry if this feels like a foolish question! Is your door open relay pulling in when you trigger the photo eye, safety edge do DOB? I have several versions of the UCL. Is there an RO relay and is it pulling in? Do you have voltage from hl1 to c18 or hl1 to c19?,
going by your latest report, double up your trailers going down to the car with a spare with a bridge. it sounds like a trailer problem particularly if its intermittant.
is it any particular direction? i wonder if you hall calls are cancelling(UHR,DHR)? i dont think its this but check it.if its all directions and the rear 1do,2do are coming in it really sounds like the do cct. the difference between when the lift is there or not is that 1 part of the cct that calls the lift and the other is that it doesnt need to do so the same common door open cct exists for both situations.
i think the system works sort of like this.
for a 10 ucl.
up hall on 2 is set.
2u sets.
hst relay pulls in thru uhr & uhc and 2u 3,4.
hst 11,12 pull in nt.
i think dz 1 & 2 make at this time.
nt 11,12 pulls in ntx.
nt 3,4 pulls in d1r,d2r.
d2r 3,4 & 11,12 energise dma and doors should open.
this sequence can be for your lift.also this is why i sadi to bridge a spare trailer(if you have 1) as you dont have to run a new 1 and/ or change it, you just bridge 2 together as its easier.
Also,is it B2 resister in there also? Sometimes causes problems
Sorry,been awhile.