I would support the bike more-or-less upside down and use a block of wood as a drift punch against the underside of the left end of the shell.
I use the same method on stuck Campag crankarm dust covers, to prevent rounding out the hex. I use a piece of broom handle as a drift against the periphery of the face of the dust cap itself. The flex that is induced always breaks the corrosive bond free.
Blasting the face of the LH cup with a torch might supplement the process, and will help to soften any Loctite (as Marten has already suggested).
A 3-lb hammer solves so many issues. I also use it with the 14" length of broom handle for truing chainring "spiders", taking some pride in getting all my c'rings running perfectly true. True chainrings allow "tighter" derailer adjustment and allow more shifting in back without need for trimming at the front.
David Snyder
Auburn, CA usa
>I just broke three tools (two 2-prong, one 4-prong) in trying to remove a
>seized left hand cup.
> It has been seeped in kroil for a fortnight, the bb doesn't look as if it
> is rusted in, who known if someone used loc-tite on it.
> Does anyone have a good suggestion before I take drastic action?