Hi Billvator,
On the residual magnetism, check the gap between the armature and the flat washer where the screw that holds the coil in. if there is no gap the coil will burn out again. there should be a buck out spring and plunger on armature. I have had these for years in older UCL. If you need info on 6850 selector email me I have S.E.O. of selectors. 25 years of wearing green pants has it's perks.