How can I fix tall kitchen larder pull out mechanism?

I have recently moved into a new house where there is a fairly new kitchen. I have a tall larder style pull out food store cupboard which has about 6 wire baskets, but it only pulls out half way. The lower track seems stuck somehow. Kitchen supplier has the most appalling customer service/follow up attitude, so no luck there! Have tried undoing various screws, but nothing visible/obvious stopping drawer from pulling out further. Has anyone any advice please. Would be gratefully received - thank you!