OP, I had the same issue w/ my Technoarm, left channel would go out intermittently. The tonearm cable was frayed at the RCA connector, apparently this is not an uncommon problem w/ the Technoarm.
I upgraded to a SME M2 9R, however, I do intend to get the Technoarm fixed eventually. When I do, I’ll send it out to a professional to rewire.
Tonearm issue
JA Michell turntable with Tecnoarm working perfectly last night when the left channel went out. After determining that the issue was not in phono stage, amps, or preamp, I narrowed it down to the left side (blue and white) wiring in the tonearm (or the left side RCA plug). Rather than purchasing an entirely new tonearm, I figure best option is to replace either the wiring, RCA plug, or both. Has anyone done this on a Tecnoarm? Is it difficult? YouTube video and Google searches didn’t turn up much.