If its the type im thinking of you would have to have the fault on to really test it or temp double up the travel cable on the selector you think mught be faulty.

1U should be up on the main selector, so then check contacts on,

nt,dzr,1u,fh(to level 4) to pick xd (geared umv).

This is similar i think to a vip type gearless selector as well(if this is the type of lift) but then your zone should have a lift at lobby level, as zone 1, then other lifts spread out thru the rest of the levels. Then if a lift is in another zone, with another lift, then the free car relay should activate to send a lift to the empty zone so check this also.