Remember that if you take the head unit out you'll have to have the Radio Code to turn the unit back on. I wouldn't take it out, at least at first. I would use a friend to hold a strong flashlight, so you can see as much as possible in the unit between the cassette tape the the tape opening, while you use a pair of tweezers or small hemostats to fiddle around in the unit. Be careful that you don't scratch the playing head (the small, metal rectangular thing that rides on the tape surface). Anyway, if there is absolutely no room to get into the unit this way, then you may have to take the unit out and apart. Most likely you will end up breaking your tape anyway...but don't fret, you can always splice the tape and use it again, losing only seconds of your music. For information on splicing the tape, do a web-search...but it is simple...just need some scotch tape and some scissors. Okay, so if you have to force the tape out and you stretch/break the tape, then use the flash light and fiddle around until you get all the tape bits out of the machine. In the future, make sure there is no "lag" in the tape before inserting it into the unit. Just take your pinky finger and turn one of the tape spindles until there is no slack. Good luck.
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Current owner of a '04 V70 2.5T. Previous owner of a '94 850 Turbo Wagon

It's not that difficult to remove the radio unit, open the top cover, if necessary, and get at the inside of tape unit.

You remove the radio head unit by depressing the two narrow rectangular recessed clips on the sides of the unit. Use a flat blade screwdriver or equivalent. The clips will spring out. Pull them the rest of the way out and slide the head unit out.

It will be easier if you disconnect the connectors on the back of the unit. Just make sure you have your radio reset code handy when you reinstall it.

When the unit is out, you should see how to remove the top cover plate to access the tape compartment.

and also - how to get it out and keep the tape working! thanks again!
-webb