No, it's not the reservoir as I have other bikes with a similar setup that don't. I believe it's a material issue for some component in the system, probably a seal or aluminum surface that oxidizes. My Ducati Sport Classic clutch reservoir does exactly the same thing, but not the front brake which has the same type of reservoir located in nearly the same position and it's well noted among other Sport Classic owners, as is the rear brake on the Huskys. I have decided it's not worth worrying about.
Shawbagga, see my long write up about how to truly fix this problem. It's at the bottom of page five of this thread (username Andy839). It's a permanent solution and also deals effectively with the rust already inside the swingarm.
Thank you my friend...after i saw your video i did the same. View: https://www.youtube.com/watch?v=M3oDIgodpME
Finally got round to the Flap Fix. I originally tried to seal up the 2 plastic rivets in the swingarm which worked but eventually the rubber flap itself broke in half. Now I have taken it apart and properly sealed the 2 swingarm rivets, basically using them to block the holes. Then I found some rubber sheet to replace the existing flap, but all I had was a little thinner and I thought it may not last too well. So I used half of the old Flap and added a piece of the thinner sheet behind it. The new flap just hangs down and the old piece keeps it straight. This way the water spray from the wheel does not get any where near the swingarm rivets and the shock is protected. Sealed up rivets in place New rubber behind the remaining piece of old flap. It just hangs down so the water runs straight off it.
I bought my Strada to service (not Husqvarna dealer) just for having my swingharm holed, the mechanic, that I know for long, told me I was crazy,, but he did drill it anyway. I was expecting the usual water drip, but instead, not a drop of water spilled..
Looks like you drilled just in front of the axle slot, correct? That a good move. I'll be copying that.
this was only an issue on early models. Later ones had the drain holes at the bottom of the plate which holds the chain tensioner from the factory.
When I drilled mine years ago, around 4oz of water came out from either side. If you're getting little to no wet weather riding in there won't be any water.
The water came out when the chain adjuster bolts were removed. I then drilled the holes...note Snow Dogs (up-side down) photo above for approx location. Then wire brush those chain adj bolts and put a heavy coating of Anti-Seize on them.
