oh boy! i had thought to buy one of those controllers as they recommend in that callas paper. sorry to hear. a real pain for you. do you replace it yourself or get someone to do it?
re: holland/china magnets, what i meant to say simply was that in looking into magnets, there are a variety of magnet "compounds" available. each has slightly different properties. and besides that different sizes might be standard from manufacturers (plan extent as well as depth). so variation from magnet source to magnet source seems quite likely.
for $3k AUD (say $2k USD) one can have the "Vitesse" a feickert product. my audio retailer says people are very happy with it. i read a review by someone on a forum saying it was a huge improvement on a la platine.
i am currently trying to get a price on the Sirius from Brinkmann. this seems very good and quite expensive i am sure. in both cases special power supplies can be used which increase the cost.
i reckon a good alternative could be the Origin Live motor kit. but then someone has to mount in the la platine housing. very permanent change which may not suit all. much more affordable.
dereneville offer motors. there is a review online (what's best) that indicated unhappiness. other people say they are great. might use same papst motor as the Vitesse mentioned above.
then there is the teres as well? this looks p good to me but again possibly significantly more expensive than vitesse.
it seems in many cases people have gone down this path and haven't found better performance than the original. so it is sort of if it ain't broke leave it type situation perhaps. my motor is a bit noisy though and of course poor @ledoux1238 you sound positively in wars so your hands are all but tied - you must buy a new motor and tell us all about it :-)