20 gauge Remington 870 reassembly problem

How to reassemble a finicky Remington 870 20 gauge. I owned a 12 gauge 870 for at least 20 years and never had any difficulties reassembling it. Recently I bought a 20 gauge 870 and could not reassemble it. The slide block and bolt kept jamming in the receiver and would not sit properly on the slide bars during reassembly. The slide bars would not properly engage the action bars resulting in the jamming. I followed the reassembly instructions as closely as possible but was unsuccessful. Step 8 of the reassembly instructions says "Guide the action bars into the receiver until stopped by the right shell latch", however when I did this the slide block would get displaced from its proper position on the slide bars and jam in the receiver. Finally, I took it to a gunsmith (twice) who was able to assemble it (although it took him several tries). I had searched for a video solution to this while dealing with it but was unable to find one, despite finding a number of comments from people dealing with the same issue. Therefore, I have tried to document the process in this video. I hope it helps anyone else encountering this frustrating 870 reassembly problem. Here is a link to the 870 Owner's manual http://www.rem870.com/remington_model...