Dual 1229 upgrades???

Buy a hardwood base from Bill at fixmydualdotcom ($95), and try swapping out the springs for Edmund Scientific 3/4 inch "unhappy balls" ($19.80 for set of 4), which perfectly fit the wells for the springs in both the tt plinth and the hardwood base. Bill's hardwood base has four small legs that should rest on some type of isolation "feet". Edmund Scientific sells Sorbothane sheets and a single sheet ($19.95) can be cut into many small (even stackable) squares that work fine as feet. Just use a cardboard beer glass coaster under Sorbothane, as it sort of "bleeds/stains" a wee bit. The nice thing about the Sorbothane sheet "feet" is that you can vary the # of squares under each base leg to achieve a level platter surface. I've done this with my Dual 721 with good result.

I'm not sure Bill agrees with the Norbornene balls in place of the stock springs, but I find greater immunity to footfalls and other extrinsic vibrations.
The direct drives with the EDS1000 motor don't seem stressed by a 3+ pound TTWeights center weight, which really helps tighten the bass. Don't know about the idlers, but a much lighter true clamp may work.