My lower dishwasher rack is rusting through so I'd like to buy a new one.

I noticed the lower rack assembly, part number AP4316872, does not include the spray tower, part number AP4113834. Looking at my current rack I do not see any way to remove or install the spray tower without breaking the tabs that hold the spray tower in place.

Can anyone provide any guidance or a section of a repair manual that would explain how to remove / install it?

Thanks!