Bosch SGS 09L08

I have this machine, and wondered about its operation.

Does this machine have a variable speed motor? Sometimes, at certain points in its cycle, it sounds decidedly lethargic; for example the final rinse: the upper spray arm always sounds as though it has a slow rotational speed.

When I first got the machine new, in 2004, it never seemed to clean the items in the upper basket properly. Bosch sent out another upper spray arm, and I noticed that the replacement was slightly different in design (missing a ‘slot’ on one of the trailing edges). It was okay until the plastic mounting showed signs of wear, then the same problems of slow speed and poor cleaning appeared again. It was yet again replaced.

The current upper arm is also showing signs of wear (a groove is appearing on the lower flange of the bayonet mount). Out of curiosity, I opened the machine on the final rinse (after the rinse-aid had been dispensed and the water was scalding), and tried turning the spray arm by hand. It seemed to have a degree of friction (I could feel the plastic sticking together), that I thought would be detrimental to efficient operation of the arm.

Why don’t Bosch at least make the arm with nylon bearings, similar to the Hoover/Candy models of the late 90’s? They seemed to zip around at a fair lick.

Now before anyone says anything, the water matrix/fill-tube are as clean as a whistle, and there is enough water in the tub.

Do other brands suffer from such wear and tear to their arm-mountings?

I remember that a Zanussi my mother had (DWS935) had a plastic arm that was prone to similar problems; the replacement arm was steel.