Stuck Lager - Pitch Dry Ale Yeast or RDWHAHB?

My brewing skills were put to the test by having to brew 2 batches back-to-back on the same day, same recipe for an event coming in late April. I brewed a German-style Marzen with 7 lbs Belgian Pilsner Malt, 4 lbs German Light munich, and Tett/Saaz hops with White Labs South German Lager Yeast. I did a single decoction for each batch, 90 min boil.

I split the vial into 2 growlers and stepped up the yeast twice in each growler. I pitched the yeast into the wort which was about 55F, I don’t have a means of aerating. I did use servomyces in each batch towards the end of the boil.

My OG was very close for each batch, 1.056 and 1.058. After 14 days I racked it to secondary, and now after about 20 days, each batch is at 1.020. Both carboys are in my basement at 64F for a diacetyl rest for the past 5 days to hopefully drop the gravity a bit, but it hasn’t budged in 5 days. I’ve carefully agitated the beer but to no avail.

Should I let it ride and lager it normally then bottle (I have to bottle condition these 2 batches), or add a dry ale yeast to ferment it more? My concern is too many residual sugars/worty-tasting beer. Samples taken during racking were good, VERY malty.

Give it some time and see what happens. Marzens have a FG of 1.012 to 1.016 so your not too far off. What mash temps did you use?

I mashed in thick at 130F for 15 min, then slowly added 190F water to bring the temp to 148F and held it there for 45 min before pulling a decoction, which was heated and held for 15 min at 160F, then boiled for 10 min. Mixed with rest mash and held at 165F for mash-out.