The luggage trial

Text: an original contemporary report-style practice extract.

A travel group tested a wheeled bag on three surfaces. On cobbles, the handle shook enough to make steering difficult. On loose gravel, the small wheels sank and the tester had to lift the bag. It moved smoothly across the station floor. The testers used the same load throughout, rather than packing more weight for the difficult sections. Their report included photographs of the wheels afterwards, but they did not find a broken part. The route revealed limitations that a showroom floor had concealed.

From the extract, identify two difficulties the testers experienced with the bag.