Punch solenoid coil problem on old Flexowriter

I'm in the process of refurbishing an old model SPD Flexowriter (from the 1950s.) When I placed it in storage, all worked ok. The storage room was dry (though not heated or cooled) and there were no mice or other vermin involved in it's repose. However, upon starting it back up (and lubing every moving part beforehand) I discovered the punch wasn't firing "on all cylinders." After disassembling the punch solenoid block, I discovered two of the coils were now open (corresponding to the two missing positions) but also, two coils had apparently shorted somewhere and changed value. From a nominal 850 ohms, the two were now about 150 and 500 ohms. I have a lot of old gear with relays (similar to these driver coils) and I've *never* had a problem with an open relay coil (that wasn't caused by obvious damage.) Is this a problem any of you have experienced and if so, have you ever discovered the root cause? I presume it is some corrosion, but the open coils were open near the middle of the winding (#41 AWG wire with about 11000 turns.) The breaks were NOT at the junction of the #41 and the sturdier wire that connects to the terminal block. Also, question 2: the Flexowriter parts list shows two different coils (both 850 ohms) used in this assembly. Four of one and four of another. I'm presuming these are magnetically polarized so that half are North-up and half are North-down in order to not have truly strange things happen all 8 are firing and you get so much magnetism that some armatures are repulsed rather than pulled, but I don't find that mentioned in the manual. I'm planning an experiment with a hall-effect sensor to verify. So far my failures have all been one type so I don't have any to visually examine while I'm unwinding them. The Flexo parts differ only in their part number - no other visible differences are seen. I am rebuilding the coils as I have an ample supply of #41 but I want to know if I need this 'normal/reverse' polarity thing if it exists. So far, I've rewound one coil with a match in wire direction to the one it replaced and it seems to be ok. TIA, Gary