Make sure your bolt is pulled back all the way, if your bolt is forward you cannot separate the side covers. If your bolt is back and they still don’t separate a previous owner may have used glue, I have ran into this before on used 880s where a previous owner glued the stock in place to stop it from wiggling.
Have old style 880 but when I took it apart it didn’t have part number 62 in the valve assembly nor an o ring behind it but it had an o ring around the section where valve slides over. Is this a different variation from yours or why does mine not go together with part number 62 in it?
Just looking for some help with an original (I believe) 880. Can someone call me at 913-660-2649 if you’ve got time to kill and answer a few questions?
John You can get by without part #62, and it may not have even been used on all the old style rifles, but you definitely have to have an O-Ring at the bottom of the pump tube or your never going to build any pressure.