Hi Binman. Sounds like the rack tail may have jammed against the 12:00 / 1:00 step on the snail. If that is the case, forcing the minute hand forward is likely to cause damage to the teeth on the hour wheel that the snail is attached to.
There are two pins on the backside of the small wheel that lifts the lever that releases the rack for striking. They may be chamfered, in which case you should be able to move the minute hand backwards (by a few minutes), which should relieve the pressure, however if this happened once, it will likely happen again.
If this is the issue you are having, you can remove the hands, and anything else that is keeping the hour pipe from pulling away from the movement. Once unhindered, lift the hour pipe along with its snail and gear and turn it counter clockwise one tooth, then let it down, reassemble, and test. This should keep the rack tail far enough away from the 12/1 step to clear it.
This may not be your particular problem but may be worth looking into as this seems to be a common issue with Frenchies.