Theoretically it sounds really easy; you can make a tape loop by taping the ends of a short piece of magnetic ribbon together and sticking it back inside the cassette tape. However, if you ever actually tried to do this, you will soon realize that it is a tad bit trickier than one would think. I spent an afternoon working out and refining this science. After many tries and many, throw-my-hands-in-the-air-and-promise-to-give-up sorts of moments, I think I have it down reasonably enough to write instructions for someone else to do it. Now you too can tape the ends of magnetic ribbon together, ?, and profit!
Step 1: Go get stuff
You will need:
A rubber washer
A razor or craft knife
Clear packing tape
A cassette player
Step 2: Open the case
Open the cassette tape by removing the screws. Carefully set them aside for later reassembly.
Step 3: Remove the reels
Remove the tape reels, but don't disturb any of the other mechanisms.
Step 4: Prepare the reels
Cut both reels free from the magnetic tape.
Put your rubber washer around one of them. This will be the wheel which will pull the tape.
Step 5: Cut some magnetic tape
Cut a section of magnetic tape roughly a foot long.
Step 6: Thread
Position your wheels back inside the tape and thread the magnetic ribbon around the rubber wheel, under the unmodified wheel, around the pulley opposite the rubber wheel, through the channel at the bottom of the tape, around the other pulley and also to the right of the plastic peg (next to the pulley).
In other words, just look at the pictures.
Step 7: Tape
Apply a small piece of double-sided tape on the inside of the magnetic ribbon, pull the loop tight and tape it evenly together.
If the magnetic ribbon is attached at an angle or any tape is sticking off the sides, your tape loop almost assuredly will not work.
Step 8: Washer
Cut a washer out of mat board and stick it on the inside of the case around the opening that lines up with the wheel with the rubber on it.
This provides more pressure on the sides of the wheel and ensures the wheel will spin. I found this to be necessary.