Don't know part numbers here, but I have 2. One is quite old and the batteries do not last long on a charge and now the top bit that had a bush to screw the centre of the heads into has split and the heads are only held in with pressure from the drive spindles. I have a newwer oone which, when new obviously had some kind of motor control as it never slowed, just stopped at some point presumably when the battery volts got too low. Now this one is acting up. It still works but even after a long charge a couple of days later it won't start on batteries, It just jerks. If you take the head off it will normally start and then when you put it on while its going it will work again for that session for about another three days doing the same thing. My guess is that its batteries again, ie the starting load momentarily brings the volts down below the cut of so it just jerks. Here we are in the 21st century and we cannot make rechargeable devices that last as long as the basic mechanics in them. I like the Remintons over the Philips as they have the edge cutting blades on the side of the heads as well as two cutters horizontally.
Very clever design, but oh the batteries are rubbish, or maybe the way the charger charges them is rubbish, I don't know.
Probably not worth repair but the last one I bought was nearly 70 quid which seems an awful lot considering the lack of complexity of a shaver. I mean what is in it, a switch mode charger some rechargeable batteries a switch and motor drive bits and the heads. The trimmers tend to fall apart since they are just a cam operated slider as far as I can tell. Brian