About snoruntpyro's entry: no idea if you finally figured out, but shell grabbed through filter can go through other enemies like shells or goombas. It's mentioned in 1st hint (about sprite collision), though to be honest I didn't understand that the first time I played. Just few days ago Minish Yoshi explained this to me. I think this gimmick could be explained better.
Also I noticed that you have no problem with earthquake puzzles in the first half. For example 1st puzzle. For me ledge is too low, but now that I think maybe keyboard (because I play on it) doesn't trigger low jump on Yoshi very well. Maybe that's why I felt lever was overprecise for me.
As for puzzle you stopped, I recognize it. So the idea is that
goomba must survive. You must bring it right.
I'm guessing that you need to
grab green shell through filter and threw it through goomba
, but this is too precise for me. So I found another solution:
spit red shell to change goomba into coin, then throw green shell into vine block. Then go quickly left, so both goomba and green shell will respawn. Use green shell to do earthquake and free goomba. Then take him into right passage and use green shell to do another earthquake.