I need help with a Dual 1219 that rumbles?

It's not clear from your description if the rumble is coming from acoustic feedback (through the air or turntable plinth) or from the mechanical parts that make up and run the platter. I think you're leaning toward the latter as the source of the noise but I'm not sure.

Besides the motor & its mounting, have you changed the idler wheel? Rubber parts can become hard with age and this will transmit a lot more noise. The spindle for the idler wheel could also be a source.

The platter bearing, spindle and spindle cylinder can also wear with use. If these parts are no longer to spec, the loose or irregular fit can cause low frequency noise.

The rubber wheel shouldn't cost a lot, but if the platter assembly itself is worn, you may be moving into "not worth it to fix it" territory. There are some pretty good performing current generation turntables that don't cost an arm to buy new.

Good luck with your search for a fix.

I believe the noise comes from the motor, idler wheel assembly as it disappears when I disengage the idler wheel. I think this eliminates the bearing and associated platter assembly, I have replaced the idler wheel itself but not the idler wheel spindle. I like the idea of having a fully automatic tt. Are there new ones worth owning? thanks Markus

There is still a possibility it could be the platter spindle assembly. When the idler wheel is engaged, it places asymmetical pressure at one point on the rim of the platter. This could cause rumble when the idler wheel is engaged.

The problem is that you don't have access to the original specs and tools used for quality control measurement. That leaves you to replace the parts one at a time, hoping the noise goes away.

As for replacing the whole turntable with a new automatic model, you'll probably want recommendations from someone more up to date on current brands.

Have you talked to them?

http://fixmydual.com/