When I changed the primary lube for the first time on my '06 dyna, I noticed the previous owner had used some type of sealant at the derby cover. I inspected the cover (harley after market cast aluminum) and found it was warped and the bolt holes had flanged slightly. I took it to work and taped emery cloth to a machinist granite, worked it over till the cover was nearly true. I reinstalled with a new gasket, torqued to factory spec only to find a leak the next day. Figuring the derby was still not true, I followed up with a light application of ultra black sealant.
I ended up changing the lube again (for other reasons), dropped the cover from the case and it cracked. Bought a new one (same model) along w/ a new gasket - install, torque to factory spec ( on the low = 85 lbs per sq. in.) and it also leaked. inspected derby after removing and the bolt holes were puckered/flanged . Inspected the case cover and it appears to be warped at the bottom but, no evidence of the bike being dropped or dumped on the outside. The gasket has no visible contact at the that section either.
Do I continue to use a sealant, try doubling up on the gasket or should I replace the case cover ($250 w/o gasket)?

 

Sounds like you need to replace your outer primary or maybe try a OEM derby cover with a O ring type seal?