Pin thing in my front derailleur

[Berk on a Bike]

Yesterday, coming to the top of a hill I had to change down into the "help the aged" gear (small ring, biggest sprocket). When I did, I heard some almighty rattling and the chain seemed reluctant to engage. On inspection I found the chain to be really rubbing the inside of the derailleur cage. In fact it was rubbing a bit in the 2nd biggest sprocket too. I thought this was odd as it had been okay in recent days.

I wasn't relishing mucking about with cables or limit screws. Then I noticed a pin was partly sticking out of the derailleur mechanism. I hadn't noticed it before but was sure it shouldn't be sticking out, so I pushed it back in using pliers. Problem was solved. The derailleur cage clearance was fine again.

My question is why did the pin come loose? It it a sign of trouble ahead? I'm concerned it might loosen again and fall out completely. The end I could see sticking out had a milled surface and it seemed a snug fit when I pushed it back in.

The pin is circled in the attached picture.

 

[mjr]

What's the model of the mechanism? Could you compare it with photos of it? It looks to me like a head might have snapped off but it's hard to say without knowing what it should look like.

 

[Tom B]

I have a bike with a SRAM front mech.
The pin that the fd pivots around occasionally wobbles out and jams the mech I usually just push it back in and all is well.

As it is a clunker I've just stuck some thread lock on it the last time it came out and pushed it in. It seems fine now. ( I used superglue at first but that didn't really stick in the greasy conditions.

I think it is just the newness wearing off.