Simple fix. Installed a 'corrugated' rubber mat https://pbase.com/9146gt/image/163336135 to protect the tray from the heavy steel bottle. Most carts bottle-trays will eventually rust if not maintained https://pbase.com/9146gt/image/163336507, this is an often neglected part of a welder, here is mine https://pbase.com/9146gt/image/163325829

The welder's non-protected floor-pan https://pbase.com/9146gt/image/163336121 also received the rubber mat treatment as can be seem in this photo https://pbase.com/9146gt/image/163336186