My comments were based on comment regarding the Ross-Tech(RT), assumed that you had not used the RT and were looking for less expense steps, looking for ideas to perform prior than spending money.I was thinking of fixing. It was a private party sale, from further reading, I am not so sure that all applies unless I prove fraud.
It's not bad yet, just some noticeably firm shifts, and seems the valve body would be the most likely culprit.
I am asking how to approach the problem. Which level of Ross-Tech would I need to DIY it? Which valve bodies and solenoid sources are good?
#1 If the RT tool is available and will be less then $100 I would have it performed, and if there are indications as to the Solenoids, etc. ask the person to give you (or you do it ) a print our or list of items that need attention or replacement, then ask for a written estimate. Then take it to the closest VW dealer and ask them what they would estimate the repair or adjustments would cost. You should not have anyone other than the VW dealer working on the transmission, electronics and or the engine.
#2 Clean trans fluid is better than dirty, but is not a good indicator of transmission performance. It sounds like the previous owners was having issues, and changing the fluid is inexpensive and is usually the first and least expensive step to correcting issues. Forget about using the fluid as an indicator of any thing more than just clean fluid.
#3 Once you have received the VW dealers estimate, and if you can still negotiate the price or return the car..... ask to see if he will pay for the repairs and if he says no than ... if you still unsure return the car.
#4 There is a reason every automaker has a warranty on their brand new cars, is because people are spending an amount of money that has a risk involved, realize that when you are purchasing a used car even if the car is prefect the day you buy it ... doesn't mean the trans or engine won't fail the first month. I had a buddy many years ago who's parents gave them there five year old Alfa Romeo Sedan. They gave him the car at age 16 because they had had so many problems with the car that they didn't think it was realizable. If I remember correctly, the manual transmission had to skip 2nd gear ... because it didn't work.
He drove the car for over six years, and never once did he have a problem, and the car was well into the 100K miles.
My Uncle, told anyone who purchased a used car he was selling, "You should put $1k aside of potential problems." That was back in 1975. Today the number would be closer to $4K.
If you have purchased the car and now own it, any Engine, Trans or electronics issues should be repaired by a VW dealer. Yes, they might charge you double, but it worth every penny.