wrote in message oups.com
Ok thanks
the drive in question is an old quantum 5.1el so

I suppose it has 1/possibly 2 heads

You suppose.

and the arm can be rotated away from the platters
completely before pulling it out!?

You got all that from Jules post? Amazing.

Now what about aligning the magnets

What magnet's'.

and sliding the 'new' arm over the platters...

any special tools etc.

The same ones that you used to slide them off.