I had that similar problem on my 1985 v65 Magna with my hydraulic clutch master cyl and also the front brake master cyl. return ports holding the front brakes applied! The small orifices will become blocked and especially underneath that stainless shield inside the bottom of the cast alumn reservoir from the dis-similar materials along with the internal condensation will clog them (recommend removing that shield to clean under that also as I did - it just pops out)! Also I used a clean shop towel while blowing out the debris inside so as to not get it all over. Great reality video (learning as you video in real time)! Those fluids should be changed out every year even if it is sitting inside as my bike does! Have a Happy New Year!