Can anyone please tell me how to change out the oil from my 02 ProSport...It's starting to bottom out when I cross railroad tracks and although I've had a 10K done on it a couple of times over the years, I don't think that they changed out the oil and now I fear that it doesn't have any in there!...It's not leaking anywhere, just bottoming out!...There is a flat round cap on top of the forks with two small holes on top. What special tool do I use to remove this cap?