Schlumpf reaction arm worked loose

I made another ride on my Schlumpf geared 29’er yesterday. I still
find it somewhat hard to ride in geared mode - at times it goes well
and smooth but I may also find I need a couple of
acceleration-deceleration oscillations to remain balanced. The play in
the cranks, especially in geared mode, seems to be a factor in this
(though probably not the main factor).

Later, yesterday, when I was in the garage for something unrelated,
the Schlumpf hang quietly from the ceiling and I suddenly felt the
urge to spin the cranks (while it hang). By that I discovered that the
nut and bolt which fix the reaction arm to the frame had worked itself
loose. I had to tighten it 3 or 4 full turns.

This was contributing quite a lot to the crank play, which now again
is a lot less. I wonder how much the riding difficulty has decreased
with my proper tightening, but I don’t really have a quick opportunity
to try this out.

Anyone else had this problem with their Schlumpf?

I had that problem once on my geared 36". The crank play gets much bigger and is quite annoying. I had not tightened it good enough. I found it rather quickly.
The crank play is not noticable any more after getting used to it, when everything ist tight.