It appears that my gun needs a new firing-pin bushing; the hole has been peened down (excessive dry-firing by a past owner? I just got the gun recently.) to the point that the firing pin is hitting too low on the primers for consistent ignition. The replacement part is cheap, but I don't know how to remove the bushing. It appears to be a simple disk that is press-fit into the hole. Anyone know how I can remove the old bushing?

Your question belongs in the S&W smithing forum. First make sure
that your problem isn't actually a bent firing pin but it does look as
if the bushing must be driven out from the rear with a small punch.
Sadly you may have fallen victim to one of the dry firing freaks who
just knows that snapping his revolver 25,000 times at the bad guys
on tv won't hurt it because no rounds are being fired.

I would recommend having the factory do this repair. Because pressing in a new bushing probably requires a special fixture to do this without causing damage to the frame of the revolver.

I'll also point out that the hole in your firing pin bushing would have to be worn into an extremely obvious oblong for the position of the firing pin strike to effect ignition reliability. It's also an area in the S&W revolver that is the slowest to show wear. A far more likely cause for off center firing pin strikes is poor timing, which is due to plain old Wear and is typically corrected by fitting a new Hand. Next up there is the length of the firing pin protrusion through the firing pin bushing, something that can be a problem on a factory new revolver. I recently had to replace the Hammer Nose on a newly acquired and nearly unused model 19-3 for this particular problem. Finally, a VASTLY more common cause for mis-firing is a previous owner tinkering with the mainspring in an effort to lighten the trigger pull. Point is that there are multiple causes for mis-fire problems and you have identified a cause that is probably the least likely. By having the factory repair your new revolver you'll get it fixed properly the first time rather than guessing at what is wrong.

Thanks for the answers- next time I'll look for the smithing forum; embarrassed to admit I didn't even look to see if there was one. This is an older gun, just new to me. The cylinder actually locks up tightly on all cylinders in both single and double-action modes, there is no end-play and when the gun does fire there is no evidence that the cylinders are misaligned, such as leading, fragmenting or excessive flash at the forcing cone. The firing pin has already been replaced and the strike-marks on the primers are uniformly deep.

Timing was the first thought that occurred to me but the bushing genuinely does appear to be the problem; the firing pin hole is oblong with a large bur at the base of the hole where the metal has been peened from repeated strikes. Primer hits are badly off-center, consistent with the position of the hole. Your thought of having the factory make the repair is a good one and I may well go that route.

On the good side I have one more item to add to the 'to check' list when looking to buy a used revolver.

Don't let anyone tell you dry-firing is harmless.
Let a pro with the right tools fix it , even a trip back to S&W would be better than a botched DIY job.

There's considerately more to this than just driving the old bushing out and a new one in.
Driving it out can damage the frame.

The bushings require a special press device with support dies and special press punches to press the old bushing out.
Other special press support dies and punches are used to press the new bushing in, then a special staking punch is used to stake the new bushing in.
This special crimping or staking punch works down the barrel.

This is not something to attempt unless you have the equipment because there is a risk of damaging the frame, and the new bushing has to fit correctly because it sets the head space.

I strongly recommend sending it in to S&W to have the experts do it correctly.

Some seriously good info here!

dfariswheel is spot on. I have a lot of experience working on firearms, and this isn't something I would tackle. Let the factory do it.

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So many S&W's, so few funds!!

I had a local 'smith (one of world renown) replace one years ago and he dinged the frame. I'll send a revolver back to the mothership if ever need another replaced.

I have replaced many of these bushings over the years, especially during the L-frame refit frenzy back in the 80's. I agree with the others who advised a trip back to the factory or S&W service center for evaluation and repair is called for.
Many special tools and gauges are required along with the new parts....and not a just little experience and training.

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Ret. LE, FA Instr, S&W Armorer