I wrote a whole long post about this but is disappeared! 
So please excuse me if this is short as I can’t be arsed to type the details again.
Basically, When I play a sustained note on my new slim phatty it doesn’t hold the volume. In other words, when I hold a long note the volume slowly fades to silence. All EG’s are set to sustain the sound.
Any ideas why this happens? Can anyone recreate this. The volume of the slim phatty is low as well (about -25db). Is there something wrong with this model?
Thanks,