TTN double problems?

[nylon ryder]

I have had this TTN 1878 double for about 4 years. It just started not firing all the time from the right barrel. I have about 6-700 rounds through it. My dad ttn was bought at same time and has less rounds through and just recently misss fired once in the right barrel. There is a good sized dent on the primer and hittin it twice will not set it off, but left barrel will. I'm guessing firing pin? They appear the same lentgh.  Have had no mis fires from left side barrel. Thanks 

[Pettifogger]

Make sure the nut holding in the firing pin has not loosened and check the pin for mushrooming.  You will get slightly frustrated as you will not find a wrench or socket that is precisely the right size to fit that nut. 

[nylon ryder]

The nuts on the firing pins were backed out about 3/4 of a turn. FYI found that an closed end 9/32 ignition whrench fits perfect. You can find tehm on ebay, mine are Craftsman.

Thanks you very much Pettifogger!