Not a recent owner, but I don't think I've posted here about it before. I bought a natural finish fretless Zenith from someone on this forum. The fretboard had some high spots, the string-to-string output balance was wonky, and the stereo output jack was intermittent. I had a luthier work on it, and he did a great job, except he couldn't resolve the intermittent stereo jack issue. After this work, it sounds fabulous and plays pretty well. I've found the black nylon tapewound strings produce the sound I like better than SS flats.
Now some 7 or 8 years later, I still enjoy and play the Zenith. Recently, the bridge pickup stopped working - well, I should say there is no signal when I select the bridge pickup. Not sure where in the signal chain the problem is, but I'll have to sort that somehow.
At one point, the knobs became so sticky that I couldn't stand playing the Zenith. I tried all the usual remedies - except replacing the knobs - with only limited success. Finally, I tried soaking the knobs in Simple Green, and that removed all of the stickyness. We'll see how long it lasts. NOTE: The Simple Green treatment produced a slight, blotchy blue-grey tint on the knobs. Do not try this unless you are willing to live with the resulting color degradation!!!
There are two issues which probably keep me from playing the Zenith more often. 1) I find it extremely uncomfortable to play sitting down. The shape and position of the lower bout just doesn't fit my frame at all, and I'm constantly hiking the bass back up into playing position. Standing up, it's OK. 2) The finish on the back of the neck gets sticky very quickly when I play and it just seems to prevent my thumb from sliding up and down the neck smoothly. Not ideal, especially for fretless. Has anyone else noticed this or found a solution? I've heard of people lightly sanding a neck to give a more satin finish but I'm afraid of causing more damage than good.