What's a larder? Model number, pictures, something to give us a clue?

Let Google be your friend.... ;-)

x2. what he said.

From HAFELE;http://www.google.com/search?client=safari&rls=en&q=hafele+pull+out+larder&ie=UTF-8&oe=UTF-8

However, there several sizes and configurations.

I'd unload the slider, check to see if it works smoothly, then load it gradually until it doesn't, and then investigate further.
If it's loaded too unevenly, it could cause it to twist.
One cause could be a mounting screw that has come loose from the wall structure.
JM2cW