The cover on the trim piece was broken so the unit corroded. It was removed and the replacement bought didn't fit, it spun round and round and wouldn't stay down. 2 more units were bought, the next 2 have trim pieces that are too large to fit in the hole. The connection cable is still present so the unit just needs to be plugged into the wire. The 3rd unit bought has the prongs positioned wrong but the trim ring (with cover) still won't fit. Not sure how to solve this from here.