Samsung icemaker won't release ice

My RSH1FTSW had a lot of problems (see previous thread) and I 'fixed' it by testing everything and finally buying a new PCB. It now appears to work but I am still sceptical.
The icemaker produces ice and the test switch discharges it but it does not do it by itself. There is a plastic feeler arm which moves up and down when the test switch discharges ice otherwise it is fixed in the UP position and can't be moved by hand.
Is this arm meant to be free moving? If it is stuck up then obviously the maker thinks the ice is full so it produces no more. If not, what stop ice production? The cubes are well frozen btw. The 'service manual' mentions the feeler arm but has no diagrams and no advice other than moving it to the ON position (whatever this means..)

thanks for any advice