If you have a Thrift shop near you, look for a small (#8) cast iron fry pan. If you luck out there, use the modified Bush Bean method (use the tall cans). Use the can opener and open up a can of Bush's Beans (55 oz size) only let it go half way around the lid and then stop. Using the handle of a spoon, insert it under the opened part of the lid and pry it up-this will become the handle. Empty the beans into a container and use later for a batch of Wicked Baked Beans
. Peel the lable off the can and wash out the can and let it air dry.
To use: place wood chips or chunks inside of can. Using the lid handle, place you new chip/chunk holder on the rack that held your chip pan. Opening should be facing up and to the left or right. Having it point toward the door will fill you face with smoke when you have to open the door.
The advantage to using the Bush Bean can mod is
a) they are cheap and can be easily replaced;
b) you can have several ready to go. Instead of refilling with chips or chunks, just swap out with a preloaded can and
c) being of thiner gauge than the original cast iron pan, it will heat up quicker and give you smoke quicker.
You might be able to call or write to Brinkmann and ask how you might go about getting a new pan.