Mossberg 144 LS

I recently acquired a Mossberg 144 LS with the Lyman peep site. I got it because I would like to try my hand at target shooting with a peep site. All my rimfire target rifles are scoped. This should be challenging. I was a bit disappointed that when I inspected the bore I found quite a bit of rust and some pitting. I am guessing it was not cleaned regularly probably due to having to remove the rear site to get the bolt out. I have been trying to get it out with some limited success. I am hopeful that the accuracy is unaffected. If someone who reads this post has a copy of the illustrated parts diagram for this rifle I would sure like to get an electronic copy. The rifle seems to be complete except for the rear swivel which is missing. I am looking for one if anyone has a spare. Still need to remove the stock so I can inspect the trigger and play around with adjusting the trigger pull. I would be interestedf in hearing from others who own and shoot this old rimfire rifle.