Hello tilasandin,
I think that every experienced bike mechanic should be able to repair/maintenance a Strida.
Of course it might be possible that she/he will need some additional info for certain details,
unfortunately very less mechanics are using the info pool of our forum 
However; I mean also that your primary problem wont’t be to find a mechanic - your actual issue will be to find replacement parts!
Several Strida 3 parts aren’t any longer in production.
Good luck,
Chris