Stuck fermentation on a grand cru

I have been fermenting my grand cru in primary for 3 weeks, and I now have a stuck fermentation. OG was at 1.084, now I am stuck at 1.024. Attenuation at 69% thus far. Fermentation temp is around 68-74 degrees.

Here's what I have done: I went and bought some more Wyeast 1214 (same as original yeast used) and created a 1 liter starter calculated to a gravity of 1.024. put the fresh yeast in it about 5 hrs ago, and now I am planning to wait about 3 days, then pitch the starter into the fermenter.

Does this sound good to you? The guy at the homebrew shop told me to make my starter to a gravity of 1.024, and wait for the yeast to get through the first aerobic phase before I pitch it. I assume that to be +/- 3 days.

I'm a little concerned that this might not be the right thing (make a starter at such a low gravity)? Should I add more starter wort at a higher gravity so that the yeast has more sugar to chew through?

Thanks for your comments.

it wont hurt you if you sanitized everything properly. You can try sanitizing a spoon or something and stirring up the sediment to get it going again. You also had a very high starting gravity and so its going to take much more time than normal. 1.024 sounds a bit low but im not sure on that one. Whenever i repitched i always use 1.040