The Dispatch | Expert | Scudo Hub

Yep, after a bit more searching I decided it was the resistor. Ordered one for about £15, came the next day. Switched it out and the blowers work fine now on all settings.

However, the actual connector had some pretty nasty wiring. Looks like it had overheated at some point and the wiring was a bit knackered. If you're ordering one, get one that comes with the short wiring connector too, just in case. Should be an easy job to cut the old one off and crimp on the new one. Unfortunately I realised after that ordering the connector would probably be another £10 or so, but could've ordered it with the resistor for no extra.