Sounds to me that PO soldered on the wrong nipple....proper one easily passes thru the 1/4 Dia adj. screw hole. You might as well cut it off....it can be heated and pulled off, but you will end up cutting off the cable end anyway.
Venhill's new cables come with adjuster and nipple already attached....no soldering required. just make sure you get length for your handlebars, and proper free length (the length of exposed inner cable required to engage the operating lever). Venhill has a form to fill out for a custom job. If you have a FAX, pm me and I'll fax it.
From your first post, it seems like you have plenty of cable....cut off the excess, solder on a new nipple, first making sure it passes thru the hole. bluto's post using a black iron pipe cap as a solder pot is a good one...use acid flux on the cable/nipple before dipping into pot. Thanx bluto', no more cable nipple soldering for me with a torch and wire solder. Thanx Venhill, no more conventional cables for me either.
One more thing...if you decide to solder on your own nipple, the cable end should be expanded AFTER you slip the nipple on....the nipple may strip off if you do not.