That was one thing I hated about my Duke 620 ---- the damn thing sprayed oil on me I don't know how many times.... loose oil lines, gaskets, yada yada.... be riding home from work --- a line would pop and you'd be covered waist down. The damn thing also kept breaking clutch lines ---- went through about 4.....everytime just about leaving me high and dry on the side of the highway.
Brian.....make sure you haven't overfilled the KTM --- if you do, it will spit oil out whereever it can. You can even blow out the countershaft seal and cause the leak. The crankcase breather will always leak a little, you just get use to it. also --- on the 620 there are a TON of external oil lines.... any one of them can let a little oil leak past their crush washer ----- make sure your bike is absolutely clean, start it....then look for leaks. The leak may be coming for some place other than what it apears.
I believe you have oil in the frame on your bike? ---- if you do, you absolutely need to make sure you follow the oil-air 'burping' of the frame preceedure in the service manual. If you don't.... you can get an air lock and ruin your engine by not letting oil go to where it needs to go. Theres an air 'burp' screw on the right side below the steering head.....
- Chip Munn is a good place to get the seal on-line. They'll also have parts diagrams on-line of just about any KTM......they'll have your bike in there for sure.
---- on the lake shore near Lake Michigan/Grand Haven, Michigan.....we have a KTM dealership that is KTM dirtbikes only --- the guys a racer and is absolutely brilliant. (even with the older stuff)
The guys name is Ron from Lake Cycle.... 616-846-3770. I'd call him and bounce your questions off of him.....
He could also order the seal for you if you want.....
The other guy to PM --- is 'Creeper' on ADVrider. The guy use to write repair manauls for the KTM's and has owned many 620 Adventures.... (same motor) He also wrote the KTM LC4 'bible' posted on ADVrider.
This guy is like LDH on CRACK. pay him the utmost respect