Marshall TSL 602 FX Loop, PLEASE HELP

I just got my TSL-602 combo in, and I realized I made a big mistake by not checking something at the store. I have a G-Major rack fx unit that needs a serial fx loop. I FIGURED that the "parallel" loop on the 602 would be like the "parallel" loop on my old Valvestate VS265R, where it's a BLEND between pure dry and pure wet; so if you turn it to the right all the way, it becomes series. UNFORTUNATELY this is NOT the case with this amp; there is ALWAYS the dry signal, and the fx mix knob merely controls how much wet signal you want blended in. This won't work for my setup!! I'm so upset! I asked a amp tech guy in a city near here if he could change it to a series loop, and he said he thought he could if he could find the schematics, which he'll charge me for either way.

Is it possible to do this? Will it sound like the series loop on the
TSL100's basically? Do you think it's possible to modify it so that turning to the left blends back to all dry, and to the right blends over to series? And is it even wise to do this or should i sell this amp and start over again. Please help... any help is greatly appreciated here.

Thanks for your reply. Yes I came across those schematics the other night, and I also asked Dr. Tube for his advice. Apparently it can be modified to a series loop which is good. I have found another problem though. Firstly, whenever I change from clean to an OD channel, there is a noticible pause in-between the change. It sounds bad. It also tends to cut off the attack of whatever I'm playing when I switch. My friend's TSL100 was the same way. But I can live with this.

What I can't live with is this: if I switch from OD back to Clean, and there is sound coming in the FX loop, the sound will completely drop out for about 1.5 seconds, and then swell back in. I can't live with this because I often will turn on a long delay, to have a distorted chord for example, contiue fading out while I discretely switch to clean and being playing over this fade out. I've done this on my other marshalls and had no problem... but this seems to be some terrible design flaw in TSL's. Does anyone know if this is something that is modifiable? Surely there is some tech around here who might know. Again any help is much appreciated.