[lugerholsterrepair]

NO! Whatever knucklehead told you that..mark him off your list of Luger experts..It is a DWM manufactured pistol. DWM made their last pistols at the end of WW1, 1918. Maybe a few into the weimar era from parts etc but effectively production stopped when the war did.
I am sure someone who knows serial numbers can come close to an actual date of manufacture.

Trigger spring with 33? You must mean some other part. The trigger spring is like a ball point pen spring..it is buried behind the trigger and has no number.