Ken;

I've taken apart 12V units, never 6V units...but I would expect that once the rivets are no longer holding things together, the remaining disassembly to be self-evident (hopefully!)...not necessarily easy because you are working against possibly decades of corrosion (which might need an oil soak to separate)...but remember that back in those days, things were a lot simpler (that goes for assembly/disassembly too!)

...replacing rivets with bolts and nuts after gaining access to innards of an assembly for the purpose of repair is a wellknown (and loved) technique in the vintage vehicle community...lesser and unenlightened men might throw such a failed assembly in the trash...if that's the case, I'd be tempted to take it apart just to learn from studying the innards!)

I seem to recall that on the 12V Solenoids, they require desoldering of the endplate (wires protrude plate from the HCC and are soldered to terminals). I haven't had a 6V unit up close and personal, but maybe someone can help with some advice/experience/pix of a disassembled unit.

I would check for VD across Sol before going to the trouble of opening it up...all of the other areas where VD can be minimized should be performed FIRST because they are all simpler and should be done anyway!...Sol rebuild would be my last resort (unless you have confirmed excessive VD across HCC with Voltmeter and are convinced this is the root cause).

Cheers