Gear Shifting Issue

[Ajax Bay]

Right. You have at last given us the clue. The band-on clamp onto the seat tube is selected depending on the seat tube's diameter. Quite often, and in your case, the one used is sized for a larger diameter tube eg 34.9mm. If yours is only 31.8mm then a shim is provided for use. The shim has slipped out partially or completely and so with the bolt in as far as it'll go the band does not clamp securely.
Measure your seat tube diameter. Then remove the band-on clamp, open it up and the size (OD) may be shown. That will give you a clue to the required shim thickness. In the last image I can see a shim designed to reduce the band-on to 31.8mm. I would have thought that there'd be two.
I've had to use a shim before, only on one bike, without enduring success. I have heard that strips cut from a Coke can are good. When the shimmed one started to give grief I found one the right (band on) size.

 

[Rhyagelle]

Right. You have at last given us the clue. The band-on clamp onto the seat tube is selected depending on the seat tube's diameter. Quite often, and in your case, the one used is sized for a larger diameter tube eg 34.9mm. If yours is only 31.8mm then a shim is provided for use. The shim has slipped out partially or completely and so with the bolt in as far as it'll go the band does not clamp securely.
Measure your seat tube diameter. Then remove the band-on clamp, open it up and the size (OD) may be shown. That will give you a clue to the required shim thickness. In the last image I can see a shim designed to reduce the band-on to 31.8mm. I would have thought that there'd be two.
I've had to use a shim before, only on one bike, without enduring success. I have heard that strips cut from a Coke can are good. When the shimmed one started to give grief I found one the right (band on) size.

There's another piece on the opposite side that hasn't fallen off yet/still taped to the part. That piece in the pic is just the one that has fallen off, so there are 2 of them. As for measurements: the diameter of the tube is 27.94mm and both sides of the clamp ring read off as 31.8mm. The seat post clamp also reads 31.8mm, but the seat post itself is 27.2mm (all according to its own markings).

 

[Rhyagelle]

Gonna buy the FD part, but the previous link is out of my country (I am in the U.S.A). I found one on Ebay, but I can't tell if it's exactly the one listed before and there seems to be 3 versions of it. Is this one correct? 😓

https://www.ebay.com/p/1167010589

 

[Ajax Bay]

It looks the same as the one I linked to earlier. I think your seat tube is actually 31.8mm (I have difficulty with your measurement of 27.9mm as that implies a very thin seat tube (given the seat post is 27.2 - according to you and the spec ).
Before you buy this I cannot see how a new one will be any better than the current one: it'll function OK if you secure it to the seat tube in the right place and with the right orientation. How will a new one be any better?

 

[Rhyagelle]

It looks the same as the one I linked to earlier. I think your seat tube is actually 31.8mm (I have difficulty with your measurement of 27.9mm as that implies a very thin seat tube (given the seat post is 27.2 - according to you and the spec ).
Before you buy this I cannot see how a new one will be any better than the current one: it'll function OK if you secure it to the seat tube in the right place and with the right orientation. How will a new one be any better?

The screw doesn't screw into the opposite side of the clamp at all, so there's no clamping force. I think that's why I was having difficulty getting it to "stick" to a height and angle. Because as soon as I untightened the screw to lower it more, it has since refused to screw into the rest of the clamp. It's way too loose now as I think maybe the crash might have broken in it more than I realized. I was hoping the new one would work in that regard.

 

[Ajax Bay]

The screw doesn't screw into the opposite side of the clamp at all, so there's no clamping force. I think that's why I was having difficulty getting it to "stick" to a height and angle. Because as soon as I untightened the screw to lower it more, it has since refused to screw into the rest of the clamp. It's way too loose now as I think maybe the crash might have broken in it more than I realized.

I wonder if you have lost a small nut which fits into the band-on clamp and what the bolt is designed to screw into?
Edit: Or you have threaded the band-on clamp, in which case a new one will be needed.

 

[Rhyagelle]

I wonder if you have lost a small nut which fits into the band-on clamp and what the bolt is designed to screw into?
Edit: Or you have threaded the band-on clamp, in which case a new one will be needed.

I think it might be threaded wrong, yea. Otherwise the only thing I can think of is that during the crash when it slid up the tube, it might have broken an internal piece like another screw/nut.