2010 Polaris sportsman 500 rear brake cylinder
 

Seems like the plunger is froze. Any ideas to understand freeze plunger. Trying to find seals to rebuild but seems like they are only available until year 2009. Do I have to replace entire cylinder? Rear Master cylinder 2010

If the plunger isn't pitted,seals are the most common cause.Partzilla doesn't have them or have you called?They show to have.https://www.partzilla.com/catalog/po...s-rear-caliper Plus ebay shows to have plenty of them.https://www.ebay.com/sch/2010%20Spor...als?rmvSB=true

That looks to be for the caliper. I need seals for the cylinder rear Master brake cylinder

Sorry,misread.. The oem is expensive,about 110 bucks for the complete m/c,hose and reservoir on ebay,but before I spent that kind of money I'd try this one. https://www.ebay.com/itm/Rear-Brake-...JYsLD9&vxp=mtr

Do you think the seals for the 2009 Polaris sportsman 500 rear Master cylinder are the same for the 2010? Looks like biggest difference is hose connectes on top instead of side

That's the major difference,hose connection. Can't remember if the nipple is able to turn,but if not they show vertical ones also that might make things easier.