Two heavy duty carriage assemblies are listed as suiting Tomma™ sliding doors, both rated to 100kg. One comes as a carriage, roller and anti-bounce guide; the other is a top-fix carriage and roller. Both are also listed for Masterglide™ and Glidemaster™ doors, which run the same pattern. When everything listed for a brand is a top-hung carriage, that is where the failure is — a 100kg door hanging off its wheels wears the bearings, then judders and lifts off the track. Before ordering, take the old carriage off and check how it mounted, because one of these two is a top-fix pattern and that is what separates them. Then measure the roller diameter and the fixing centres, and note whether an anti-bounce guide was fitted to the original.