In this situation, adjusting the return flow will not solve the problem nor will adjusting the heat input. This still was built by someone who does not know how to design stills. Due to the incorrect plumbing design, this column will always flood when someone attempts to use it correctly-- -----Hi Paul ,i agree with your this comments, but last time i dar not to say so,sometimes ,it hurts if you say the truth directly. This still was born with design problem, unless replace tower column,if do so,the experienced engineer must be in place to check and redesign which involve more cost.So the best way for owner is my way to use it.The money already paid, it would be painful not to use it.
The second thing you mentioned, i did not know which company you were pointing to,so i will not comment this. About my company, i have confidence about our quality and design, and we did not get any design yet from any company yet.