Please let me know what I'm doing wrong.
I hate to say it but there's a fairly good chance this machine simply will not do what you need. Quarter-inch stereo tapes come in two varieties:
1. Half-track stereo. This uses the entire width of the tape for two tracks, which means that it can only play in one direction. This a high-quality format used for mastering, which is what the 5000 would have been designed to do - putting the tape on in reverse will play the recording backwards.
2. Quarter-track stereo. This has the recording split into half the width of the tape. The quality is reduced but you can flip the reel over like a cassette and play two sides worth of audio. This is most likely what your tapes are recorded in.
So. If you have a machine designed to play back 1/4-track recordings, you can put a 1/2-track tape on it and play it back fine, albeit with slightly less fidelity. But, if you put a 1/4-track tape on a 1/2-track deck, you will get both sides playing at once, one of which will be backwards.
Now. I don't know much about the 5000, it being amazingly expensive and out of my league. Do you know how many heads are installed on it? It's probably either 3 or 4.
If it's three 1/2-track heads, you've got a problem. If it has 4 heads, one of these is often a 1/4-track head so that it can play back 1/4-track tapes, i.e. exactly what you're trying to do. In which case there should be a switch somewhere to flip it over. (The Otari 5050 is like this)
If it is a 3-head 1/4-track deck, which unfortunately is quite likely, your only option would be to replace the playback head with a 1/4-track one (this will make things awkward if you ever need to record on the deck!).
You could probably get some from JRF Magnetics, but they are
not going to be cheap, especially if they have to be custom-made. You would also need to perform an azimuth alignment on the machine after replacing the head. It would be quicker, easier and cheaper to find another machine for this task, and keep the 5000 for recording work
