I'm a total newbie with HO trains. I've been buying engines and cars, mostly on ebay, for my grandson. Most are Bachmann. Some are missing couplers. One arrived with a loose coupler and I couldn't find the screw for it. The coupler on the other end of the car is mounted with a small round-head screw. The coupler has a small hole for the screw. On ebay I bought some Bachmann EZ-Mate Center Shank Medium no 78005 couplers, but the mounting hole is too large to hold the screw head. Can anybody tell me where to look? This is my first day on this site. I know I must sound pathetic, but thanks for some education.
I use CA (super glue) to mount all my couplers. The other option if you can't find a screw is to use a small washer.
I buy my small screws at Lowes...yes the big box Lowes. Look in the aisle (usually the outside aisle) where all the individual nuts, etc are and up above are the brass screws in the little packets. Probably the #2 - 1/4" or 3/8" will work fine.
If this is for a Bachmann engine go to the "Parts, Service and Information" link at the top of the page. Look up your model of engine and order the screws from there.