I have a 10 year old FirstCo Air handler. I am having problem with it and looks like the board needs to be changed. Couple of questions 1. Typically will the manufacturer sell boards for obsolete models? 2. How much will the board typically cost? The HVAC tech from oil company scared me saying that just the board will cost more than $500 or more. 3. How easy is it to install the board? Can it be a DIY project? Is it just screws or is it much more complicated?