It's pretty easy. Pull off the stock, find the pins that holds the firing pins in, knock them to one side with a drift pin and change the firing pins. The firing pins are spring loaded but not with a lot of tension. I use a small magnet to pull them out. The pins holding the firing pins do not need to come all the way out for the firing pins to clear. They can be changed with out taking anything else out.
Both top & bottom firing pins have springs in them.
If you look at your top & bottom cross pins( pins holding in FP)
Top cross pin should drift to the left & bottom cross pin to the right.
If I remember correctly. This will allow cross pins to stay in holes &
Allow you to remove FP without removing cross/retaining pins. Take &
Clean out the FP holes & FP springs they should have carbon buildup
On them from being fired over the years, sometimes they get pretty bad
w/dirt & carbon build-up. Install new pins,springs & walah.
Easy as pie.