I assume that you are in the States ?

Swop the machines over to allow the Physicians machine to playback and yours to record

If the second unit has seen a lot of work playing back tapes then the playback heads could be dirty or worn

Dirty heads can be cleaned using either meythalated spirits or surgical alcohol and a cotton bud or a clean cloth, there is even a dedicated head cleaning cassette kit available from Radio Shack .

Click on the link below

http://www.amazon.com/Radio-Shack-44-1162A-Cassette-Cleaning/dp/B000AN2L5E

To clean the heads you need to remove the power open the cassette door and press play (Certain decks have a small lever which need to be pushed down manually burt which is automatic when you install a cassette , this allows the heads to come forward)

Once the head has come forward wipe it with a clean cloth soaked in either of the above (I prefer the Surgical Spirit as it leaves no residue) You should see a fairly black mark appear on the cloth as you rub, this is the oxide from the tapes surface

To get the best out of a head they need to be de-magnetised which is not so easy

Let me know what happens

Venexcsd