I hope I'm not muddying the waters, with my dullness...
I was a bit confused last night regarding what the test actually did. I've got it now, but last night I installed exdialer just because everyone was saying its the way to fix this issue. But, after sussing this out this morning I double checked and exdialer failed (i.e. showed my my imei). So, uninstalled it and checked both dialerone and the stock dialer, both succeeded in only showing the USSD code.
So, maybe my stock dialer was ok the whole time and I didn't really test it correctly, last night?
Or, the act of installing dialerone, has done something to sort the problem (if that's possible)???
I've since uninstalled dialerone, and double checked the stock dialer, and its all good now. For what's worth I'm on the 940 repack.