Collected my bike today. Top bush in one of the legs was worn (showed me)but they changed them in both legs.
Spindle problem I had when inserting through the central spacer was, as mentioned, the bearing(s) weren't quite home enough to hold it in place.
Spike in revs when slowing down to walking pace was explained as the system sensing engine speed was too slow for the wheel speed ? It doesn't happen with the clutch pulled. It has been subject to a software update now ....
Also software update has improved the take-off from stationary (apparently)
Was a different mechanic who actually phoned me to get an accurate description of the problems after I took it in, and came out to speak to me with the replaced parts when I collected .
Not ridden yet so we will see in due course ....