You need to rinse your tanks just like any other piece of gear, especially when they are banded.
To remove existing salt, put them in the bath tub and sponge them down with a solution of 50% white vinegar and water. Whoever VIP'd them should have removed the salt build up before re-assembling them, so if they did not point it out to them and ask them why they did not address it when they had them apart
Assuming you have decent quality bands and they are properly assembled so that the tanks are truly parallel, you should be able to carefully loosen one band, slide it down and clean under it, then re-install and tighten and then repeat the process with the other band. Just be sure not to put any loads on the tank that would stress the manifold.