Hydraulic system stopping while operating

[Richcart]

We've haven't had any problems with the hydraulics until this fall. We were camped in VA and the temperature was dropping into the low 30's and 20's. When we were packing up to leave the slides were sluggish and stopped 4 times while retracting them. We would lose power in the coach and then it would come back in a few seconds. We got them retracted and the same for the level up system; stop and go. I checked the fluid level and it was low. It was clear liquid so I added a quart of brake fluid; it was that low. It still does it but now only once or twice while pulling in the sides, but the power goes out and then comes back on. The fluid is just below the full mark on the tank. Any ideas? We bought our Monty used in September 2018 and have been full time since May with no problems until now. Any ideas?