@milleniumaire – Sorry to hear that. Here is a creative idea (Just for more long term benefits), I would look into ‘3d printing’. They are now making Vacuum adapters with it like this one:
Check if your local Uni and I’m sure they’ll be able to help you out. They now have one of these machines that can help you make spare parts and save in the long run.
Re: Which is worse in your opinion, overloading or underload
Overloading hands down. Overloading is bad for the motor, under loading is bad for the drum (Over heating but depends on the settings). If the motor is done, your machine is done 🙂