I have a Remington 870 Wingmaster 20ga that I absolutely love. Its a mid-60's production and has functioned flawlessly. The only issue I have been having is when taking apart the gun for cleaning there are 2 long thin steel plates inside the receiver that have small prongs on the end. The one on the shooter's right side always falls out and seems bent at an odd angle. Are these able to be replaced or is this normal? What are they called? And does anyone have any sort of reference of what its supposed to look like? If I'm not being descriptive enough, its the metal piece that you push in on to allow the slide and bolt/carrier to be pulled out fully during cleaning.

Shell stops. They are staked in place to prevent them from falling out when you remove the trigger group for cleaning.
Your local gunsmith can easily restake them. Special tool gets it done easier than home repairs.

They are supposed to have a bit of a bend in them. Don't mess them up by rebending them. They sound like they are working fine when the shotgun is assembled.