Long PCR stuck in the wells :-(

[Hong Dang]

Dear Bionetters:

We are trying inverse PCR of 6 kb plasmid according to Barnes' mixing polymerases
strategy. Some primer sets worked real well, while others not so well. However, 1
set of primers produced either nothing or heavy EtBr band stuck in the well.

Anybody has any clue as what the stuff is and how to "move" it down to the right
size PCR band?

Any input is greatly appreciated.

Hong
hdang at channel.neusc.bcm.tmc.edu