You can change Brushes yourself if you've been on the pyroban course, just need to invest in the smoke generator equipment to confirm the motors sealed correctly after completing.

I'm not trying to be cheeky (please, no offence intended) but have either of you been on the pyroban technicians course?
I find the time scale quite understandable when you see the scope of what their doing, you get a good tour of the shoreham factory too.