Which is one of the reasons the earlier DA 50's could only be tuned to work correctly at one end of the operational range. Too small a carb generates that problem.

If one has an older Brison and they suspect carb problems every cure has already been noted in this thread. How one goes about checking things is another story. Most instantly blame the carb. others will blame an ignition.

So pull the carb and the insulator block it's mounted on. Get some 220 wet or dry paper and put it on a dead flat surface. Now run the insulator block, both sides now, don't skimp, back and forth over the paper to generate and assure a flat surface. Replace the gaskets with new ones. Use a little, meaning very little, sealant on both sides of it before re-installing. Don't be scared, buy a rebuild kit and do the job that probably needs to be done. Make sure you blow everything clear before you put it back together. Of course you did make a few notes about how it came apart, planning ahead for the assembly process, right? Those somewhat astute would be able to look at the old gaskets and see the impressions made on them by their associated component... Likely the welch fitting doesn't need to come out so don't get antsy over that.

If in the end you have to buy a new carb, so what? Do you really think these things are supposed to last forever? Are you that naive? If the carb costs more than you want to pay you have a choice. Buy one and fly or don't buy one and don't fly. That's easy. Just don't complain to everyone about how you think the parts are over priced. Nobody asked you to get involved in the hobby. You did that all on your own and accepted the consequences when you did so.

Some of you folks make every thing so difficult.