On Saturday, January 7, 2017 at 6:33:31 PM UTC-8, Theodore Heise wrote:
Hi all,

I have an early 1990s Rodriguez tandem with a rear bottom bracket
in serious need of overhaul. The cranks flop severely.

I've pulled the cranks and the lock ring on the left side, but the
adjustable cup won't come out. It turns about a quarter turn, but
then gets too stiff to turn further. It has no flats for a wrench
instead having holes for turning with a pin spanner--so I'm unable
to put a lot of force on it.

I've soaked it with WD40, but still no joy. Any advice for me?

Ted, it all depends on what confidence you have in your mechanical ability and if you're dumb enough, strike that, willing to buy a tool that you're probably never going to use again.

http://tinyurl.com/hcds8af

This is NOT a magic bullet and as john has recommended you have have to work it back and forth until you finally free it.

The modern sealed bottom brackets with the spline is a whole not easier to install and remove.