try adding about 10ml of sodium hydroxide 5N per liter and a half of the color developer. you can adjust the rate higher or lower if needed as well, but it doesn't take much. diluting the reversal bath also helps, you can also monkey with the first wash temp to warm up the color balance.
I find it neccessary to add sodium hydroxide to every batch of chemistry (kodak) we use for our wing-lynch machine at work. for years, we ran the rev bath at 60% and then kodak advised to use it at full strength with the newer chemistry. we had nothing but problems this way. after much tinkering with our control strips and process--we now have almost perfect plots. I have never seen them better, and both EPN and Provia run great.
here's what we did: put the prewet back into the process. diluted the rev bath to 60%. added 10ml sodium hydroxide per 1.5 liters. extended the final wash 5 minutes extra.
If you overshoot the balance on the sodium hydroxide--you can shift it back with sulfuric acid. You can eyeball this if you aren't using control strips. Since you shoot EPY--if you can get any (fresh) of the old control strips, they'd be perfect, since they were on EPY stock. The newer ones, are more sensitive and don't have the same control measures really. The sodium hydroxide works more on a cyan type balance. It's not used to bring the blue HD plot up anymore. As far as I can tell, the reversal bath concentration seems to be more of a control here, but you afe already diluting this, so I would try the sodium hydroxide.
btw--you mention using washes between the steps except for rev-color developer. you shouldn't wash between the color dev and pre-bleach either, if you still do this? the pre-bleach needs the carryover color developer for stabilization.
hope this helps--go to Kodak's process control website and the Z-book and much of the control stuff is free online now.