@robssofwynyard I might post again if I run into any issues while working on this. I would really appreciate any advice from those with experience. Thank you.
@robssofwynyard You've disassembled and serviced it three times! The third time must have been quite difficult. I admire your skill.
I think the problem with mine is probably due to damage to the stopper and guide roller. I'll try my best to fix it. Thank you!