Red Blooded Biker
I hadn't been looking forward to this job, but was really pleased that the filter retainer came out without as much hassle as I thought it would.
I ground down the largest 'Easiout' that I had in my tool box...just enough so's to grab the rounded off sides of the retainer, then put a bit of pressure behind the shifter &....click...it came undone.
The replacement part was £6.20 part #7703-8017-000 from all good KTM dealers. The original 'o' ring should be ok to reuse unless it's damaged.
I put some moly grease on the threads of the new retainer, which has a 13mm AF or T45 receptacle for securing it in place.