Mongoose Gear Shifter/V Brake not going back past 4

[Suresh]

Hi, I'm new to the forum and this is my first post. I don't quite know how to explain it but will try to do the best I can.

I have a Mongoose mountain bike which I picked up for nothing. It had 2 broken spokes which I fixed quite easily. Bike works really well apart from the gears for the back sproket. It will change from 4 to 7 and back from 7 to 4 but then doesn't go any further. I have uploaded a Youtube video

http://www.youtube.com/watch?v=ht5nzhGsk88

I don't know what the parts are but there is a little cog that works like a ratchet. Once this gets to 4 it reaches the max for the lever. i.e. there are 3 more clicks it can go, but the lever has reached its max 'push'. I hope the video explains better and I hope someone can tell me if this can be adjusted or if I have to buy a new part.

Thanks.

[nfmisso]

How are you rotating the pedals when you are shifting? It is not obvious in the video that you are.

Derailleur systems REQUIRE that the chain and cogs be moving when gears are changed. If not, it will shift a gear or two each side of nominal, then jam. Any attempt to move beyond that point results in a damaged shifter and damaged derailleur - repair is not possible in that situation.

[Suresh]

Hi Nigel, thanks for the advice. I wasn't rotating the pedals in the video but prior to taking the video was riding the bike testing the gears. The situation was the same, I couldn't change past 4 back to 1. I dismantled the shifter today (don't know what I was going to achieve doing this), but after I put it back together it was worse!! Now the shifter lever is stuck and doesn't change at all. Back to the drawing board, might get a new part or take it to a bike shop. Thanks again.