Whoa! Don't go spending that money just yet. First, if you are using a black powder substitute, that is your big mistake. It doesn't work worth a darn in a flintlock. You must use only real black powder in a flintlock. Next, look at your touch hole. Is it centered on your pan and just about level with the top of the pan? What is the size of the hole? It should be about 1/16 inch in diameter. Too small of a hole can significantly delay ignition. Make sure that your fire channel is clean and clear. After you have made any of the needed corrections, turn your attention to your lock. With an empty pan and an unloaded gun, cock and fire your lock while you carefully observe the sparks. Does it spark properly. Not enough spark usually means one of two things; either your flint is not sharp and needs to be re-knapped or replaced or your frizzen is too soft and needs to be rehardened. The latter is not likely with a T/C, they are almost always good and hard. Also be sure that you have a good flint and not some crappy (in my humble opinion) soft chert. If you don't have a good English or French flint, order some from someplace like TOW or Dixie Gun Works. Be sure that they are the correct size for your gun. How you charge your pan can make a difference, too. One of our very knowlegable contributors to the Forum, a man who goes by the name of Plege (I'm not sure that I spelled his name correctly) did some high speed photography to see where the best place to place your pan charge is. His findings suggested that the best place is to bank your pan charge up next to your touch hole but not plugging it. Use about 3 to 5 grains of powder in your pan. While 2f will work in your pan, 3f or 4f seems to work best.
I used to have a T/C flintlock and it was all original. It fired instantly with no hesitation so I am pretty sure yours will too and you will not need to spend the money for a replacement lock. However, if you do decide to replace your lock, L&R is a very good choice. I think it would be my first choice. One caveat, seldom will a replacement lock be a true "drop in". they will almost always need a bit of fitting to get them to work. Nothing all that difficult, just a bit of careful fiddling.