Welcome...and congratulations on taking the plunge into flintlock shooting.
Before you do anything....look at the pictures posted and determine which generation your lock is.
I have a 1970's vintage 50 caliber flintlock Thompson Center "Hawken style" rifle.
I'm one of those folks who got my 1st generation lock replaced for free from Smith and Wesson, who owns T/C now. That was about 3 yrs ago and I have NO idea if that option is still available. In my case...when I acquired the rifle the frizzen had been broken off. I called the service center and asked the very nice lady if they still supported the lifetime warranty that was in place when I purchased the rifle. (It is a "family rifle" so to speak...I bought it for a cousin back in the 70's and got it back after he passed away. ) She told me that they did warrant T/C products but that parts availability could be an issue. In my case..they emailed a shipping label to me, I sent the lock in and got the new, 2nd generation lock within the same week.
IF...if you have a first generation lock, I can't help you as I have no experience with those. A buddy of mine down here went the "L&R Drop-in replacement" route. He found it was far from being a "Drop-in" and hasn't been particularly happy with it. On the other hand...I have found the 2nd generation T/C lock to be a pretty darn good piece of equipment. If you look around, you can find a Lyman frizzen that has been slightly modified to be a direct replacement for the T/C frizzen. Of course, you can buy a Lyman yourself and do your own fitting...cost is about the same either way, approx. $20.00. I recommend doing this. I wasn't impressed with the T/C frizzen. I would also recommend that you try to find a pkg. of Thompson Center Touchhole Bushings. T/C. part # 7327. They come 2 per pack, with a small allen wrench for installation and removal. I literally stumbled on those one day at Dick's Sporting Goods. I thought they looked interesting and decided to give them a try rather than drilling & tapping the barrel for a Chambers vent liner. They are the next best thing to Jim Chambers liners you can get for your T/C rifle, and don't require anything other than take out the original, and screw on of these in.
At the end of the day, with those inexpensive modifications, IF you have the second generation lock...you're going to wind up with a VERY decent flintlock rifle that doesn't "give up" much to anybody's custom.
As to the rifle itself...I also recommend changing the sights. IMHO...those T/C sight are awful. But perhaps that's just me.
All in all...my 50 cal, slightly modified T/C "Hawken style" flintlock performs with excellent reliability and sufficient accuracy that it's my go-to rifle for Deer and Hogs.