I can't find it but you need Larry Pina's Test Pattern Generator for the B/W Macs. It will display the measurements and alignment of the screen. It's in his Mac Secrets and upgrade book if you can find it.

I'm sure the yoke needs a but of an adjustment. A slight twist to it will show greatly on the screen so move it in tiny increments to level it out. The same with adjustment magnets. And be careful. Make the adjustments when you turn off the Mac and turn it back on, and repeat as needed. Do not go poking about back there with the Classic on! If you're lucky it will kill you, as the pain from the electric shock will be greater than death itself!