My first one, which is just over a year old, I just lubed with some 20,000wt silicon differential lube (for RC motor transmissions). Works like a dream.
Ordered another one for my office desk a few month ago: noisy clacking, bad tensioning, etc. -- a complete nightmare. (Glad it wasn't my first one). So I completely disassembled it, cleaned off all the rough plastic sprues with an x-acto knife (48 point edge mod), lubed the core (Lubix Ultimate method), reassembled, lubed, re-tensioned the screws off and on for a few days, sanded the corners as they had rough spots (I used a nail file), and now it is even better than my original GuHong.