I'm pretty sure that the 'yellow thing' is a mains suppressor, comprising three capacitors in a delta network, and it's certainly the culprit. The second line of print on it (obscured at the start) is probably decoded as '1 off 150nF and 2 off 2.5nF'. It's followed by a 'Y', which presumably identifies the capacitors as Y-Class. 3-capacitor delta suppression networks are used all over the place, made by many manufacturers, and available from places such as RS Components. Cheap. Component values won't be critical. No need to hunt for a 'Makita' one, just get one around the correct values (there won't be much choice) and a suitable physical size. And search the 'net for delta suppressor capacitors or similar, for more info.
One leg to live, one to neutral and the third to ground (earth). The spring will just be the ground lead's connection to the motor's earthed frame.
Incidentally, these days, X- and Y-Class suppression caps are usually metallized polypropylene, and fail in a dignified manner (if at all). I have replaced several older metallized paper suppression caps which failed with smoke, flames, bangs and a disgusting smell. Before the fireworks, they often swell, so there's sometimes some warning. For some reason, they are still available. Description in a 2013 RS catalogue contains 'high safety regarding active and passive flammability due to metallised paper construction'. Diametrically opposite to my experience! They seem to last about 20 years – well out of warranty, so who (except me and thee) cares?
Edited By Kiwi Bloke on 26/01/2020 10:12:40