Left Rally RK200 not answering: how can Master mode be detected

Problem:

Right Pedal shows 3 LED flashes (means left Pedal not found). No LED Blinking from left Pedal, no Connection to Edge Computer.
I chatted with Garmin service and get a repair set FOR FREE! The problem however remains. Battery checked. Battery problems are out of question.

In my opinion the pedal pivot shaft may be the source of the problem.

Questions:

1. How find the left pedal out his role as Master?
Garmin Service stated, that the litle round control panel is identical for both sides.
Does anyone know, how the left control panel find out his role as master? Eprom? Jumper?

2. Replacement of pedal pivot shaft
Unfortunately Garmin does not offer pedal pivot shaft. At Amazon I found a dubious offer 
https://www.amazon.de/product-reviews/B0CTCPH2GB/ref=acr_dpx_hist_1?ie=UTF8&filterByStar=one_star&reviewerType=all_reviews#reviews-filter-bar
Does anyone know this offer or another one?

3. May be, the pedal pivot shaft is not the problem
Any othe idea?