I have a gas fireplace with a SIT 820. The house was built in 2003 including the installation of the fireplace. It worked fine for 13ish years and then the pilot light wouldn't stay lit. I had someone look at it and he filed the pilot light area with flint paper and it worked for a short time but then reverted to the pilot light not staying lit for more than a couple of minutes. I disconnected the gas line and blew it out with air using a pump and it didn't fix the problem. I planned on just replacing the SIT 820 unit but wanted to check here for anything else I might be able to try before doing that. I also read some posts on replacing the unit but haven't been able to find a comprehensive install guide or video so I'm not too clear on the process of removing the old one. Thank you in advance.