One article suggests using a MCM idler tires as a cheap replacement for the Alesis part. It is correct to say they are cheap. Clean the deck surface particularly near the idler wheel where you'll find bits of rubber shed by the idler. Before touching the head assembly rotate the drum with your other hand so that the wipe will presses against the drum gap between 2 of the heads. Brace your hand on the cross support above and to the front of the head.
Any vertical movement can destroy head alignment requiring head replacement.
With your other hand rotate the drum so the head pass under the wipe. A fairly high pressure can be tolerated if you hold your cleaning finger steady. Work the the heads back and forth one at a time until no dark residue is recovered. Let the heads and tape path dry thoroughly before inserting a tape.