mmm, sounds tricky, is everything else going well? that would be a bonus if you have no other problems and eliminate causes
sort of sounds elecrical, something is obviously happening at a certain stage, you have checked as best as, only guessing, could it be a loose connection somewhere, because it is suddenly stopping for no reason and randomly?
give all the wires a look over and make sure their not worn, attached properly, may help?T:
can not offer specialist support, other than my DIY experience
