I would get my springs from Wolff unless I was making an order with DWA.
Wolff has factory spec trigger return springs and reduced power ones too.
And they have 7.5lb. & 8lb. hammer mainsprings also,I'd just buy the kit they sell and maybee another factory one being yours is probobly broke.
I would remove the grip and sideplate and cock and pull triiger to SEE what's happening.Being carefull of the paw for the cylinder as It will want to pop off with the sideplate off.You'll see the trigger return spring it rides on the hammer and the leg rests on the back of the trigger. If it's broke you'll see it.
I plan on making a big order with Wolff soon as I need several springs kits for some of my guns + mag springs,recoil springs etc. & I will be ordering thier Kit for the DW 15-2..
Good Luck!!!
I'm Lovin my DW, The Most Accurate Handgun I Ever Shot!!
Dan Wesson