ATC250ES harsh clutch engagement, transmission noise on downshifting

[TheRadBaron]

This is the first auto-clutch machine that I've had, so bear with me. The clutch on my '85 Big Red seems to engage kind of harshly, especially on downshifting. I have the idle and the clutch adjusted correctly as per the factory manual. I've kind of gotten the technique for upshifting smoothly. I just shift kind of slowly and let the revs fall while I'm still holding the shifter up to let the centrifugal clutch disengage. That seems to work well.
However, when I downshift, the transmission makes rather loud clunking noises when I press down on the shifter, and I can't seem to let the lever back up slowly. I just take foot pressure off the lever gently until it jumps up and slams the clutch back engaged. I've tried slightly increasing and decreasing the clutch play adjustment, but it doesn't have much effect.
I once rode a buddy's auto-clutch Honda 230 4-wheeler, and I remember that it behaved similarly. Is this normal behavior for an auto-clutch? Or am I doing something wrong or perhaps have a mechanical problem on the trike? I really like this trike and I don't want to tear it up.

[tri again]

some say wet clutch oil specific for motorcycles is the only way to go.
some say cheap 10 40 works with no problems at all.
Most say oil additives are all bad.

I have a few auto clutch machines that can be slipped just like a manual clutch if you let off slowly on the shifter
and some that just jump no matter how slowly the shifter is let off.

Never bothered to worry about it.

Maybe this thread will get us both a good answer.

Pretty sure they're supposed to slip gently into gear like a manual clutch.

Maybe the fix is new clutch shoes and non grooved 'clutch baskets', if that's what they're called.
or a simple change to the right oil for wet clutches if we're lucky.