UDATE EDIT: Wow - I just realized after posting my comment today that Orgiva's message was two year's ago! The first several postings under Electric Locomotives topic list old postings first, then the current postings. So, I'll need to look at the dates of the postings before I post a reply......lesson learned. But regardless, I for one would appreciate Orgiva updating us with the final solution used to fix the slow running Uintah.
Orgiva - Sounds like one of two issues: Wheel gear out of alignment causing torque on the motors; failing motor or other electrical short issue. Yesterday I started to install an LGB 65003 diesel sound unit into a person's LGB 2063 loco by first testing its operability on a ball bearing roller track. It had a noticable tump noise on the front axle. I opened up the motor block looking for a damaged gear but none found. I then lifted up one wheel set and reset it, and put the cover back on, and no more thump noise. People trying to move a loco's wheels could possibly cause this.
I've found most electrical operating problems are caused by a failing motor. So, if the first approach above doesn't fix your issue, I'd buy at least one LGB E126050 (62201) Standard Motor Short Shaft and swap it out with each existing motor to find the defective one. You can find these motors cheaply in the USA for $60 (OnlyTrains.com) or $58 (Uplandtrains.com) plus shipping. I bought a brand new one recently on eBay.com including shipping for $49. I've also seen them selling on eBay.de Germany for similar equvalent price. In my mind, the price of one or two motors is well worth abetting the aggrivation you're experiencing.