Idlehour
Welcome aboard TF from another happy MS owner.
There are lots of after market sources that might have what you need if you know dimensions. If not you might pose that question to other 40DC owners.
If you look in the Marlow-Mainship builders section there is a "MS Parts" sticky thread (remains up top). For other makes & models other than the late year 34T/ HT the parts are not searchable but follow the links and you cab scan through thumbnail pucs of parts and click on any that look similar.
Generally the pics contain source and part # info.
It's not the easiest way but does provide helpful info for many hard to find parts.