Advice on transmission

[TJMAS]

Need advice on what to do. Have 03 xc90t6 with 180,000 miles on it with the original tranny(l'm one of the lucky ones). It has it's moments for awhile now where it will slip occasionally when starting out but then it won't do it for a couple a months and then it will start again. I know the filter and fluid have never been changed but have been leary to at this point because I've read instances of failure after doing this. Not that it's anything like a flush but I had a front axle a year ago that the plug in the tranny end had come out and it had leaked lots of fluid through the shaft. I had replenished the fluid regularly for a while until I was able to find the problem and replace axle so a high precentage of the fluid is not original. I have gotten a code refering to 3rd gear in the past but not regulary. Should I try flushing tranny and replacing filter or would it bring on failure at this point? A side note to this is early on when I was still having it serviced by the dealer I was told by the dealer that this tranny did'nt need filter and fluid changed. I now know that's not the case with the t6. That dealer no longer sells Volvos. Thanks for any help.