I've Repair at 100 but I'm not able to repair items to 100%. Nobody else can. When I played Oblivion I was able to repair any item fully. Is there another way of doing this in this game?

Strange, with a skill level of 100 and the necessary parts, you should be able to repair the things just neatly.

To what extent can you repair them?

Sorry. Maybe I've read it incorrectly. I was refering to any of the the sellers who offer a repair job to repair an item to 100%. They don't seem to be able do that & I seem to have a job finding many of them, other than Moira Brown & the 2 guys in Rivet city & they are not always able to repair some items. Any suggestions of more capable repairers?

Invest into Crazy Wolfgang, once he's got all his goods capped he'll be able to repair anything to 85% condition.

Another way would of course be to look up the repair lists via G.E.C.K. and modify them so you can repair everything yourself. Some mods already do this by adding Scrap Metal to almost every repair list, you'll see yourself bunkering that stuff instead of giving away for XP and Caps.

Thanks. I'll give that a try.

http://fallout.wikia.com/wiki/Repair#Non-player_characters_who_repair

-Gunny

Also if you have the Mothership Zeta DLC, Alien Epoxy can repair your rare and unique weapons to 100 %
It's free , you just have to pick it up and it has zero weight.