The function as you noted is correct. Merely pull the front trigger and the fun fires. It seems to have been adjusted to not function correctly as a set trigger. After being set, the lever must jump up HARD to kick the sear loose of the cocking piece.

Sounds to me as if the kicker (main spring) spring is turned (loosened) too soft to kick the lever up far enough to fire the action.

I have a spare double set, single throw trigger if anyone wants to send me some $20.00 for it. It, of course, is a ML trigger and is quite period correct for about 1800 to 1830, as far as I know. Original -That I don't know either, hence the low price which includes shipping - HA! They are a pain in the posterior, trust me.

The Mauser double set, double throw triggers are wonderful triggers and beautifully made, usually.