Yeah, it's SO tough trying to diagnose problems here. We've discussed many of them over the years, but you still have to look at every potential problem.
Given we've been here 10 years, there will be a percentage of the smokers (they are electric) that don't work for some reason, but that's why we say call CS first.
Given they've been working as designed for so many years, they're work, but sometimes we have to get to individual things that might not work.
One other option. Don't use BIG chunks. Keep in mind the wood has to burn to create smoke. Sometimes cutting the chunks in 1/2 will help.