Jeff:
Are you referring to the copper threaded rod?
In most cases this can be corrected. Clean the read of all lubricants.
Get two books for equal thickness.
Place the rod across the book suspended by the edges of the rod.
Using your fingers, roll the rod back and forth gently and note where/when the rod arches up.
Carefully push/bend the rod at its highest curvature to flatten it out.
If you do this over a number of iterations you can get pretty close to true again. You need to be careful not to apply too much pressure as this will make things worse.
Derek