By testing the coils with an ohmmeter from the top wire on the coil to the steel contact in the sparkplug boot, you can at least establish that there is continuity from coil to sparkplug. If there is a bad connection in the wiring, and the coil is generating power from the flywheel magnets, then the charge will try to get to ground any way it can. This results in damage to the coil.
Another common problem with coil replacements is that either the upper or lower fine coil wires are not tucked in enough toward the coil. The spinning flywheel hub makes contact with the fine wire, rubs off the insulation in no time, and causes a short.
Condenser wires need to be bent downward to prevent contact with the flywheel hub.
If you can post a few pictures, there may be a visible problem that someone might notice.
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