Originally Posted by
JanMM
If your crank arms wobble, that could be either a problem with the crankarm/crank axle interface or with the bottom bracket itself. Either way, taking it all apart is a good plan and referring to Park Tools repair help is a great first step.
If the problem is in the crankarms, they will wobble independently. If the problem is in the bottom bracket, the crankarms will wobble together.
A crankarm extractor is a semi-frequently needed tool and there really isn't an adequate work around for having one. If you're planning to work on bikes, put one on your shopping list.
That bottom bracket might be a different story. After removing both crankarms, take a hammer and an expendable screwdriver to undo that lockring. The right side will almost surely be a left hand thread. Then try to find a wrench to fit the bottom bracket itself. The right side is called the "fixed" cup for a reason. The trick is to keep the wrench engaged on such a narrow flat. It might help to use a semi-loose clamp to hold the wrench engaged.
Good luck.