Thanks guys.
It only has one motor, I think 1600w so not that powerful.
I've stripped it apart and it all looks good, but I will spray with WD40.
It has a small electronic part, inside the head (which is yellow and about the same size and shape as a postage stamp). Not sure what it is but it is slightly black on one side. I may explore this further.
There has been no odd noises or indication of any problems. To be honest it's run as sweet as a nut.
Don't spray with WD40 it's conductive!!!!!
First if it's still under warranty speak to company first.
The small electronic component is a capacitor - it is used to help start the motor as it helps energise the second coil as it knocks the phase 90 degrees. They can fail but then the motor doesn't really start to spin without assistance.
If it's tripping the mains it can be due to one of a few things.
1. Excess current it should only trip an over current trip in fuse box? Check motor spins freely (check with NO MAINS). Can you see the brushes? Are they worn out - too short? Is the commutator (copper or brass strips the brushes touch) work or nice and smooth?
2. The Earth Leakage trip (RCD) trips. Takes half or all fuse board out. Some how electricity is 'leaking' to earth!!! This can be VERY dangerous if you connect to a customer supply that doesn't have RCD as the 'leak' could run through YOU and kill you!!! You need to work out where the fault is, it could be the insulation on motor is breaking down or maybe the carbon from brushes just needs cleaning out?
Make 100% sure it's unplugged before working on it.First thing to check is the supply cable. Check for nicks, cuts etc then look for weird kinks or sharp bends as internals could be damaged. Then look at the switch, does it look blackened? Follow the wires to the motor, are they all intact and dry? Then have a good look at the motor, bearings OK, commutator looks smooth, brushes still applying pressure?
My guess if everything is dry is motor is failing. Speak to who you bought it from if it's under warranty and see what they say.