Improving MP-1's SS channel compression.

Hi all,

I really like the MP-1 solid state clean channel with its compression.

But I noticed there are some distortion artifacts when I want to
achieve a very deep compression, by any combination of turning up OD1
and OD2 more or less. No matter how I try to set it up, there is some
buzz on transients (not just in the attack: the buzz persists well into
a note). This is even though OD1 reports no clipping and the overall
volume is nothing (I can play louder on tube clean with no such
distortion).

I have an NE5532 op-amp in the compression circuit. (Put that in
myself.)

But the compression chip is the original, 25 year old NE572. I'm
thinking of throwing out that out and popping in a new SA572. Maybe
they have improved the gain cells in that thing?

Has anyone tried it and has it made any difference?

The distortion might not be clipping; maybe the compressor is
releasing too fast and fluttering, causing inter-modulation with the
tone? I haven't looked at the circuit in a while, but I seem to
remember that both the attack and release can be tuned via some
resistors and capacitors.

Has anyone experimented with tweaking the attack or release?