100% certain they're mounted the correct way to the plate. I've done enough computer heatsinks and processors not to make that mistake...
That said, I tried cranking it over a few days after this happened. Started immediately up, so the problem is intermittent - and while it may still be the module, I want to run a few tests on the coil. Didn't have time to play with it (or think about it) last weekend, and probably won't this weekend, so it'll have to wait.