I recently bought a an ACOG. I went to Trijicon's website and asked them if they knew when my model was built. I gave them the serial number and in two days they answered it was made in 2010.
It's a 4x32 TA31F and the tritium needs to be recharged.
I called Trijicon and this is what they told me.
I send them the sight, shipping on me. After they receive it they do a Free diagnostics on the sight. They put together a work order with a price quote and call me before any of the work is done. If I want the work done, they needed all the money from the quote. If I didn't want the work done, they send it back to me.
Over the phone they quoted me the cost to recharge the tritium. $188.00. They told me that the tritium and the filament needed to be replaced at the same time because they are one piece.
Hope that helps