I'm trying to find someone to repair my super sledge I got off tabitha and my armor but I can't find a repair vendor please help.

I saw a few merchants roaming the wastes and they were able to repair my stuff.

When you talk to them is there a separate dialogue option to repair or do you do it through the barter screen? I've explored around the bottom part of the map. Goodsprings, black mountain, helios one, repcon, novac and I haven't found any repair vendors?

Its a separate dialogue. There is this old lady who can repair your stuff near Helios 1..

Do you know which direction from helios one?

Old Lady Gibson is in Gibson Scrap Yard located due south of HELIOS One

Thanks.

majour knight at the ncr base where the giant statue of the ncr guys shaking hands hes in the hq part

you can do 100% repairs with the ncr at bottom left corner of map to all your gear if you have the caps for it