Die_Bogener is correct in that it won't start without a record. It will just rotate the platter a couple of times without moving the arm.
However, if the Beogram hasn't been used for a long time, it may seem to start correctly, swing in the tonearm and lower but then lift and stop right after the needle has landed on the record. This is due to oxidation on contacts inside and in most cases it will wear off in normal use.
The correct thing to do is to have it serviced, cleaned etc. but you can also try playing a record several times, maybe 20 times or more and see if it starts behaving correctly.
The above applies to all the Beograms in this series, Beogram RX, RX2, 1800, 2000, 5000 and derivate Beocenters.
Martin