H&R .22 revolver problem

A friend has an H&R model 929 .22 cal 9 shot revolver that was having several light strikes. I replaced the mainspring with one from Numrich, still getting light strikes. At least 3 out of 9 every time, they will fire the second time around. Also, after firing all 9 rounds, the spent casings will not eject from the cylinder. I have to push them out from the back of the cylinder. There is also some play ( back and forth) in the hammer when it is in the fired position.

I was told it had not been fired much in the last 8 yrs.
It wasn't cleaned/oiled before it was put in a safe last time it was fired. No corrosion but very dirty.
I used Winchester .22 LR to test fire it after a cleaning and new mainspring.

My questions are,
Why would I still be getting light strikes after the mainspring replacement?
Why are the spent casings getting jammed in the cylinder?
Is the play in the hammer normal? Should i be looking at the sear components?
What can I soak the cylinder and other parts in that will remove the buildup and not the bluing?

Thanks

Try a different ammo. Are you getting actual light strikes or is the ammo not going bang consistently? That seems to be an issue with some of the more common bulk pack ammo.

If you’re keeping the chambers clean it could be build up causing the hard extraction. It’s possible, likely even that there are some rough spots in the chambers. That along with the fact that .22LR ammo is notoriously dirty, especially typical bulk pack ammo could be causing the hard extractions.

Not really sure about the hammer being loose without looking at it.

If the cylinder face is dirty under the case rim, the hammer energy maybe getting absorbed. Cases may stick when the cylinder walls need a good cleaning.

Check to see if there are places where the firing pin has hit on the edges of the chamber. This comes from dry firing and puts a raised place in the chamber that might prevent rounds from chambering correctly.