I have a recently acquired Remington Portable #2, it doesn't look like it's had a lot of use but something is off with the escapement that's causing me grief.

At random times the escapement hangs up, either with the space bar or by striking one of the keys. There are two teeth that hold the carriage in place on the escapement, the bottom is stationary, there is one on top that is supposed to swing out of the way but at times binds against the teeth of the escapement itself so the carriage won't advance. I removed the cotter pin that connects the space bar to the mechanism and the problem disappears (in as much as it can be tested without the space bar). It feels like something in the assembly is rubbing (there is resistance to the stroke of the space bar) but I can't see where it might be. I know a picture is worth a thousand words but I can't post links yet. Any suggestions at all would be appreciated.