Gnasher will correct me where Im wrong or am bike agnostic -
But that could be the swing arm bearing, one of the bearings in the suspension linkages, or possibly even a rear wheel bearing. When you say you have up/down play how are you seeing/feeling this..? When an MOT tester checks all of the above for free-play, they stand behind the bike and put both hands on the rim of the rear wheel and gently but firmly pull upwards a few times. And as others have asked, how much free play are you seeing/feeling? If the movement is almost imperceptible, then that's most likely an MOT advisory. But back to narrowing down where the play is -
But that could be the swing arm bearing, one of the bearings in the suspension linkages, or possibly even a rear wheel bearing. When you say you have up/down play how are you seeing/feeling this..? When an MOT tester checks all of the above for free-play, they stand behind the bike and put both hands on the rim of the rear wheel and gently but firmly pull upwards a few times. And as others have asked, how much free play are you seeing/feeling? If the movement is almost imperceptible, then that's most likely an MOT advisory. But back to narrowing down where the play is -
- If you haven't done so already the first thing to so is remove the rear wheel, then with the sprocket carrier and axel in-place put your knee/chest on the top of the wheel and again pully gently but firmly on the axel and check for free-play - there should be none that you can feel, if there is you should replace all the wheel bearing as you can replace just one (good pattern bearings are cheap enough now)
- When the rear wheel out same as before grab the ends of the swing-arm and check for free-play. If you feel any its either a linkage bearing or swing-arm bearing.
- Remove the suspension linkage and using the bolts that go through the roller bearing check for lateral movement, as in up/down or diagonally. If there is any movement the bearings and/or the bolts will need to be replaced. Note - I think the bearings in the linkage may need to be pressed out and new ones pressed in, but don't quote me on this.
- If your wheel bearings and your suspension linkage bearings are fine, then that only leave the swing arm bearings. The only test I can think that 'might' show wear is to hold both arms and try a gently but firm twisting motion. If there is any free-play then replace the bearing and check the swing-arm excel for wear.