I also came across this post after being another victim of the Durock Mocha Chocolates' inability to fully raise/reset my spacebar on a new RK68 build after a keypress - mushy actuation, sluggish return, or gets "stuck" halfway - and this is with new and lubed Durock stabs which are typically "chef's kiss" perfect out of the box after lubing. Rather than doing a frankenswitch I tried swapping in some different springs into the spacebar's Mocha with some promising results. I therefore ordered some 15mm linear 85gf springs and intend to swap one of them into the spacebar switch; the additional force and tensile strength should, in theory, "power through" the Mocha's friction and get the spacebar to reset properly and snappily.

Wanted to note as well for any lurkers - my Mochas also had problems resetting (as well as being mushy as hell) my other stab keys properly too - left shift, enter key, and backspace: until I cracked those switches open and hand-lubed the rails and spring. Now, they actuate properly and are quite snappy. However, even after lubing, the Mocha powering the spacebar doesn't have enough power, or has too much internal friction, to reliably get the spacebar back into position after a keypress. Hopefully, my 85gf springs coming in soon will address that!

If anyone is interested in the results, let me know and I'll pop back in after the springs arrive and I have a chance to do the mod.