High Doppelbock FG

[gxm]

I brewed a Doppelbock recipe 3 weeks ago, fermented with Wyeast 2206 at 50F, pitched to a yeast cake from a Helles.
The OG was 1.076, and the FG is now 1.025 (corrected for temp), and the FG hasn't changed for the last week. The wort sample tastes a little too sweet from my taste.
I brewed this as a partigyle, and the small batch fermented to 74% AA with US-05. If the doppelbock fermented to the same degree, it would be at 1.019.
As I prefer beers to be less sweet, I'm wondering if I should try pitching some other yeast, such as a champagne yeast, or just RDWAHAHB?

The recipe:
Caramunich 0.82
Lt Chocolate 0.49
Crystal 150 0.16
Germ Lt Munich 9.81
German Pils 2.80
Mashed at 152F for 60 minutes.

 

[Short Drive]

From the Fermentis Tricks and Tips brochure:
If the wort does not attenuate fully, there are two possible areas of concern:
a) Brewhouse
b) Fermentation
Try adding new dry yeast of the same strain to a small quantity of wort and aerating vigorously. Leave in a warm room for 24 hours and recheck the gravity to see if the wort can ferment further. If it does, changing the yeast generation for a new one will correct the problem. If there is no change, the wort is not fully fermentable and the fault is in the brewhouse procedures/raw materials leading to an unfermentable wort.
If a brew is seen to be slow fermenting, discard the yeast and pitch with another generation. Avoid pitching yeast recovered from very high gravity fermentations if possible.