Mechanical.
Replace the belts and the idler wheel rubber parts.
Clean and lubricate everything. All very common by now.

Tape end is sensed as lack of tape motion using a magnet and a hall sensor.

Martin

Thanks.

Can I get these parts and if so where do I get them from please?

Is there instructions on how to do this task please?

It seems I can unscrew the plate that holds the cassette tape to get to the mechanism underneath, but do I need to pull the  tape drive mechanism out completely by disassembling the whole 7007 unit?

I have the correct parts and I can provide instructions (take no more apart!).
PM or email me.

Martin

Hi there, I have, I think, a very similar problem to this. I have replaced the two belts in the cassette mechanism; they were completely disolved. Now if you fake a cassette being inserted play and rewind seem to work (all things that should rotate do) but fast forward doesn't.

With a tape inserted it is worse. rewind works but for Play the heads momentarily engage and then release with a clunk and nothing happens.

Any help gratefully received

Correct belts or german/chinese/portugese "Ebay"-belts?

Did you also replace the idler wheel rubber parts?
Clean and lubricate the mech.?
Right reel brake on the correct side of the braking flange (felt pad still there?) or is it bent? 
Left stabilizer for tapehead bridge broken off (steel ball missing)?

Martin