hello ,,i imagine you have the dredded shoot one and throw one out the bottom problem,,had a few 1400s in my day and everyone i owned had the same problems , ,,have you tried popperts gun parts?
http://www.poppertsgunparts.com/webdata2/search.html if it's not listed give them a call and mabey they can help ya ,,good luck and seems a shame that winchester never redesigned the problem child ..i always felt they handled well if they would have just functioned as good as they looked ,,

..hey also check gunbrokers.com mabey someone has one up for auction ,,i'd do a search of "winchester shotgun" or just "winchester" ,,there will be alot of hits i know but sometimes what ya want may not be listed how ya search a site,,by searching a brand name sometimes you find more than a specific part or model
bigcurt