[swo4rd]

I solved a similar problem with picture hanging wire and Kroil...i inserted the picture hanging wire and when it stopped, i attached it to a reversing drill and pushed it on until it cleared...there were at least a dozen blockages in the pipe...after all complete, i got a small diameter plastic coated picture wire, pushed it through and then frayed the end then took about two hours to pull it slowly through thus having the effect of a wire brush...there was a hole in the line which was easily patched when i restored the tern coating by tinning the pipe with 30/70 solder. Heat applied to the pipe outside at stubborn spots seemed to help...it was a two person job...To patch the hole i rand the stranded wire back into the pipe with flux on the ends and then heated up the hole area and flowed the colder in...the frayed wire had the effect of a "solder sucker" and i pulled the solder right back out.