This thread covers how to repair a common issue found in all DD walkmans that use a center-gear type mechanism. The problem manifests the following: you press play, the mechanism latches into position, then unlatches immediately. This can also happen in FF/REW. The problem is caused by old grease in the latch/stop mechanism levers, so as they remain in the position when the cassette door is still open. The thread does not cover the disassembly of the mechanism, which is covered here: http://www.walkman-archive.com/articles/sony-dd-repair-guide_01.html You need to remove all the parts necessary to replace the center gear. Then proceed as described in pictures. NOTE 1: that the mechanism does not need to be removed from the plastic frame, here being removed for illustration purposes only. NOTE 2: The 2 levers must get fully driven into position by just the action of the 2 springs after cleaning.
Older boomboxes with a ton of moving metal parts also have the same issue, it's so nice when they get cleaned and re-lubed and everything moves with precision.
Something in regard to testing these levers work correctly (before and after the cleaning/repair): push the bigger lever arm down and see if it comes back into position just by the force of small spring as shown in attached picture. Any slight resistance should be adressed, the lever must spring back without any resistance.
