I suspect the 'bike mechanic' is correct. The adjustment bolts loosened over time. Blue Loctite, the only one that would be in use for this application, is not designed not to ever allow loosening. It slows loosening. For most things that is as good as NO loosening. For a trike front end ... not so much. But the front ends of sophisticated trikes like an HPV Gekko has 'toe' and 'camber' parameters that are different when the trike is laden or unladen and the correct adjustment of these settings are not intuitive. The dealer that sold that trike is the best entity to perform the service. Second best is having someone at HPV communicate the service manual to the o.p. or their designee. Sadly, most standard bike repair facilities treat recumbents, even two wheel recumbents like they have no relationship to the bikes they regularly service. Not even drivetrain systems that are one and the same with a regular bicycle will they touch.