Hey, cassp.... I am surprised at how long it has taken you to get around to asking the actual questions that are bothering you. I also find it astonishing that, coming from a synth background, you STILL haven't even bothered to learn how to save programs (UPGs), probably the most fundamental thing to learn on ANY programmable keyboard. Get an XK-1? You'll STILL have to learn how to save your presets (like if you want to change the Leslie character, hint hint...)
Ranting only gets you so far, and is easily avoided by posting your questions at roland-arranger.com BEFORE the frustration sets in..!
But seeing as how this is posted here, now, I'll deal with it here... Unfortunately, Fran's answer is only partially true. MFX#83 can only be inserted on regular Tones, NOT the HB (drawbar) section of the G70 (which is what I believe you were really asking about). So there is no way to edit the Vib/Cho of the HB section. You CAN select V1-3 and C1-3 and store them to User Presets, but you can't change the actual CHARACTER of the HB Chorus, nor it's depth (which is all the Vib/Cho Vintage parameter in the MFX seems to do, IMO). The HB section appears to be '60's' only. A REAL VK Organ offers you access to these parameters (but you would have to learn to save them, in any case!).
There are only a few regular organ Tones that don't already have some Vib/Cho sampled into them (which ruins them, as far as I am concerned) to use with the MFX rotary effects (and MFX#57, the VK rotary doesn't have the Vib/Cho section), so, other than those few tones, you are going to have to get used to the Vib/Cho sound in the HB section, I'm afraid... (I checked the sys-ex codes, and these don't access those parameters, either).
If you are using your G70 in a recorded project, BTW, I would suggest laying the organ down on a separate pass to other Parts, and turning all reverb OFF. The HB's reverb send is pre-Leslie

, so if you want an ambient Leslie sound (don't we all!), put the reverb on to the organ part with a plug in (or track through an external reverb).
But, in future, try to post your problems BEFORE you get to the point of wanting to sell your arranger... OK? Trust me, you will find no other arranger any easier to use, on the whole. Even far less expensive arrangers (and less capable and live-sounding) will be no less complicated, and if you aren't going to be happy with anything less than being able able to tweak whatever parameter comes to mind, no less complicated arranger will make you happy either.
You've got a quandary, don't you? You want microscopic editing detail, but you want it simple too...

Best of luck with THAT one...
