Holco - thank you for the report.
Regarding leakage - ideally you want none, but practically a small woofer enclosure leak doesn't do much. Are both channels the same? Of serious concern is if the woofer enclosure leaks into the midrange sub-enclosure. Push both the woofer and passive and see if the midrange moves. If so, troubleshoot.
Regarding foil coils. I await your comments on that change. News from the research front: foil alloy is considerably purer than wire alloy. As I've mentioned, Thiel used 6-9s ultra aerospace wire from 1978 onward. By 1995 that wire was no longer available and we used 4-9s specified as C10100plus. That seems to be the best wire currently in use, except for specialty boutique producers such as Cardas. I have learned that ERSE, Jantzen and other high-end suppliers now top out at 3-9s C11000 @99.9% with higher oxygen allowances. Jantzen specifically disclaims audible benefits beyond this C11000 grade, etc. etc.
My personal experience is to the contrary, having spent the summer of '78 comparing wire. Some auditory brains hear the difference. I am currently exploring a solution strategy.
Beetle - your FST coils and hookup wire meet the C11000 spec. But your FST coil winding was less than best. I await your experience with Cardas hookup wire.
Audio inductor foil meets better than C10100. It is as good as the original ITT 6-9s aerospace wire that I secured in 1978. So the generally accepted higher performance of foil coils might be attributable to some combination of foil skin effect reduction, tighter wrap and purity of alloy.
Lotta mystery.