The 46-MOD doesn't require the trans to be pulled, but would be easier to do. Is it a necessary mod? That's debatable. Change the fluid for sure. A "pan-drop" would get the bulk of it out, but not all (I'd think that's ok, but others may not agree). If you do a pan-drop only, let the vehicle sit overnight for as much of a drip-down as possible. Also look into an air compressor to blow out as much of the fluid out of the lines & cooler. Get new filter and gasket kit, and run with it.
The servo's easy to check. Pry the retainer ring out with flathead screwdriver. Don't go jammin' and yankin' around, just take your time, and it'll pop off rather easily. The same goes for the servos. You'll want to be careful about placement of your tool of choice (big or small driver). Don't use a sharp-edged driver. If the driver slips, you could cut or damage a descent seal. Once removed, check the seals & bore to ensure no damage. If you see something that doesn't look right, take a pic and post it. If the seals look good, reinstall and run with it.
As for pressure...
#1 - Is this an OEM (stock) PCM? If so, leave alone. If not, see #2.
#2 - Has any of the trans tables been modified? If so, how much? See #3 & #4.
#3 - If you've done your own tuning, let's see the tune (or tables).
#4 - If someone else has done your tuning, advise them of your issue after confirming the simple trans troubleshooting seemed ok.
Now, to really troubleshoot your trans, it'd be best to see how you built it. Obviously, that's a good bit of work for those who don't normally do that sort of thing constantly (like me), but more sets of eyes are better than one (believe me). Now, that I think about it.... how much fluid did you put in the trans? Do you have a shallow, OEM deep, or aftermarket deep pan? Obviously, fluid level is important, and capacity differs with each type.
