I think I have a stuck fermentation, and am requesting some assistance/advice.
Indeed you do!
I chilled the wort to approximately 62 degrees, and pitched a 1000ml starter that fermented for 2 days on a stir plate, included a wort fortification after the 1st day, yeast nutrient, and with one vial of White Labs Zurich Lager Platinum Strain.
According to any calculator, you underpitched by a metric crap ton. Using JZ's calculator, you underpitched by 10 fold. According to Kai, you underpitched by 4 fold. Use this calculator next time to get off on a better foot: http://yeastcalculator.com/
A week later, the gravity was at 1.050, and I racked to secondary
Don't rack the beer if it isn't at the terminal gravity!
I made another starter with two more vials of WL Zurich Lager yeast and let it go for 24 hours, then pitched and re-aerated; that was 5 days ago.
This was a good move! Now leave it there.
I planned to extend the secondary another 6 days (which ends tomorrow (2/4/15). Today, I checked and the gravity is at 1.040.
Leave it in the vessel it is in until you reach terminal gravity.
The diacetyl rest is set to kick off tomorrow afternoon (I have a programmed BrewBit controller) - diacetyl rest is set for 72 degrees F for 3 days.
You should know that beer/yeast are not on your timetable. You must follow the yeast's timetable. If I were you, I'd be raising the temp to encourage what little yeast you have in there to actually finish up, but I wouldn't dare rack it until it reaches terminal gravity (if it ever does).
Here's a quick run down of what you can do next time:
1) Chill to below 50F.
2) Pitch at below 50F and then let it warm to 50-52F.
3) Oh yeah, pitch a LOT of yeast. Follow online calculators if need be.
4) Don't transfer it.
5) Check gravity before doing anything.
6) Raise temp a bit if you're past 50% terminal gravity, but don't rack it.
7) Raise to a d-rest (62F) if it needs it.
8 ) Now you should be at terminal gravity.
Hope that helps!