Hi guys,

I just bought a cheap old mountain bike that has some slippage in the smallest back gears and wasn't changing into the smallest gear at all (I've managed to fix this by winding out the H limit screw on the derailleur). The slippage doesn't happen on the biggest gears at the back, but once changed into the 4th biggest one and below, the slippage happens on every gear whenever you put reasonable pressure on the pedals.

I've been googling the things that may cause slippage in gears and I have checked the following:

* Chain stretch - looks perfect
* Wheel alignment - looks perfect
* Worn cogs - they all look pretty good
* Crooked derailleur - this is what I think the problem is, but I'm not sure what it *should* look like, or exactly how to straighten it

I have uploaded some photos (h ttp://imgur.com/a/laoZU) to see if you kind folk could confirm for me that the derailleur isn't straight, and perhaps suggest a way for me to correct the issue.

If I'm off the mark and it could be something else, I'm open to suggestions!

Thanks in advance.