Lawn Mower motor problems

[Blaggins]

Hey guys. I have a Bosch Rotak 34R electric rotary mower, only a couple of years old and not used that much.

Last weekend whilst attempting to cut the grass I noticed the motor sounded higher pitched than normal (slight whine) and then I noticed quite a pungent burning smell.

Opened it all up and it was very clogged with dry grass and dirt, which I cleaned out, including all round the motor. However the machine still struggles and smells, and I can see a lot of sparks from the motor where the brushes touch, but I’m not sure if this is Normal or not! The brushes seemed to have a lot of length in them, but were a little uneven on the end - like they’d chipped.

1. Are the sparks normal?
2. is it economically repairable?

I have video but I can’t seem to upload it, so I’ve attached a couple of screen grabs for now.

thanks.

 

[Burnerman]

Naturally enough these small motors need to be cooled by air which is often filtered through foam, and if that has been compromised then the motor will be upset. A motor that has a 'plasticky' smell is a sure sign of insulation breaking down, likewise excess sparking. All the motors spark to some degree but if you can see the sparks circling the copper contact area on the commutator it's a fair sign of an exit soon.
As for an economic repair, it depends on what ebay has to offer, I guess.
John