Just to add to this post, because itīs been extremely helpful to me, facing the same challenge of "splitting the egg".
This addition is about the DC46, which is the non UK version of the DC47 (the same except for the plug, I assume...), a handy and small vac, so it would have been a shame to lose it.
The motor was burnt out due to a blocked airpath.
Buying a new motor assembly at 60GBP and more was close to the market value of the vac, so no real option. After some hesitation, I managed to disassemble the motor unit, the biggest challenge being the removal of the rubber cover. After that, it is mostly straightforward. Now I could recognize the engine type, which is shown in pic 1. (SDS1304AZD)
I could not find that particular motor anywhere, neither new nor used. But a few slightly different numbers came up during the search.
Looking at pictures and technical data, the DC40 motor (non ERP) looks similar mechanically and electrically (SDS1354AZD). Of this motor, there is a good supply of new and used units, so I managed to get one used for a decent price. The number is shown in picture 2.
The remaining pictures show the similarity. However, having them side by side, there is one slight difference, which is the carbon brush assembly that sticks out wider in the DC40 motor. And of course too wide, so it did not fit in the housing. Luckily, the brush mount in the engine body is the same, so itīs a straightforward swap. After the swap, the motor fits perfectly into the housing.
Motor is running fine now and everyone is happy. Another unit saved from an unfortunate death