I have a straight out of the box Dremel Trio that has sat in the box for several years since purchase, so isn't under warranty.

On plugging in, it starts and dies every time the trigger is pulled.
The time it runs varies from about 0.5 seconds to maybe half this or less.

I have had a look inside and can't see anything obvious. No heat damage etc, but then, it hasn't been used.

It uses a microswitch with an electronic soft start. As in picture attached.

Is this likely to be the cause of the fault? Should I replace the microswitch, (or get someone with better soldering technique to do this) or is it likely to be a fault elsewhere?