Never heard of JFM, John, but a quick search comes up...with next to nowt! Italian websites etc? And one 'jfmhelmets' site 'Under Costruction' [sic]
to be honest, maybe it's a chance to bin the helmet (especially if it's a bit beat up) and get a new one, different make, with better visor availability
No offence, no patronising, just an alternative view