Haaaa! I think we may have finally solved the leaky forward head!
For years now we've been fighting with the forward head and how it back fills. Originally we replaced all the guts, hoses and all and it was GROSS! yet we still had a backfill problem. I changed out the joker valve with a similar duck valve, still leaky. Changed out the hoses directly leading from head and siliconed fittings. Still leaky. This week I took it apart again and decided to swap out the duck valve with a tri-valve.....voila!