It's a weep hole. You probably need to rebuild the rotary union or it just might have something stuck in it. You can take it apart and check the o-rings. You will need the spanner tool to removed the c clip. Isn't hard. We should have a rebuild kit in stock if you need one. If you don't have a water softener and use certain "rinses" it might not come a apart then it means a new rotory union. You will know immediately when you take the c clip off. If it doesn't come apart then your ordering a new one.
I just had the same thing happen to me, if Olson can't help you call Rotovac. They sell new and rebuilt unions. If you have a powerwand your not using, you can take one off of it and use it.
So you have to use a water softener to properly run the 360i? What type of rinses? Can you use emulsifiers that contain water conditioners/softeners in them without damaging the 361i? Do those water conditioners really work. I've got a fair amount of hard water where I am but I've used supposed chems with softening agents in them and still find a lot of hard water deposits on my tank and on my equipment.
it is really no different from anything else out there....if you have really hard water or run a lot of chemicals threw your system or excessive heat it will take out the o-rings...
we have to rebuild the wand valves..
sprayers...
or just about everything that we use that has o-rings...