Rainbow E series with sparkling engine (by 2 users)

Dear Ladies & Gentleman,
I have a vacuum cleaner Rainbow E Series wich stoped working. I verified the lower security shaft that is working perfectly. Dismounted the device and noted that the engine is not clogged. There are two golded kind of engine breaks (opposite one each other) wich I dismounted to verify both string's strengh. They seem a bit weak and the brakes a bit used. Experiencing the engine, I turned it on, with the empty canister in it's place and I noted that, when I make the machine's restore (red button), the engine spins for a bit making some sparkles and it turns off again(that I know is the security system working). Now, my problem is not knowing that, if by having those used "engine brakes" (and I will know their exact function with a mechanic at my work place), is there missing some small pieces that keeps the engine working as it was for this 8 years of life of that wonderfull cleaner (used to many times in my cars too).

Thanks for all the attention and any good help ;-)