hmm, tricky one that… id remove it if at all possible, the brittle plastic they use in the outer tub obliterates with no effort
if its got a welded tub, its more difficult, u could try taking the heater out (with plug out) and see if its there … not an easy task, and a pig to put back in, its best to change the heater most often
if its got a tub thats screwed together, it is possible to pull the lifter out from the drum by pulling it forward and it will come out, u may need to replace it, sometimes they break
that will allow you to look in the drum for the coin
either way, the coin needs to come out
hth