No info on this site (that I can find) about Airbaths / spabaths, so here's what I found.
Compressor (in the loft) gradually lost power to blow bubbles through the water, and we lost interest until granddaughter came along. Blower is now almost 20 years old and runs, but not much power.
I phoned Airbath who said drawings are unavailable, brushes wear out etc. and so solution was to buy a new one - about £200 inc. VAT, delivery, charge for using Credit card etc. (?!!)
Stripped it down: essentially there are two end caps which have the mounting brackets attached. The motor is contained within a double-walled cylinder, held together by the long screws. The idea appears to be that air is drawn up from the bottom and between the twin walls of the cylinder, then sucked into the top of the motor, over it and blown out through the centre at the bottom. I guess this all helps to warm the air / cool the motor.
The upper end cap has sponge stuck around it on the inside. Maybe this is to try and dampen the noise? I believe this was coming away and obscuring the inlet to the motor while it was running - only a guess as it's not visible with it all boxed up. I removed the foam, and also removed the plastic obscuring the holes in the upper end cap.
It works a lot better now, although air is maybe a tad cooler.
Steve Milner
December 2009