Although not familiar with a 6200,the same basics should apply
1/ Is the hydraulic fluid up to the proper level?
2/.Has this just started since the south went cold? You might have some water freezing in the system and causing a blockage
3/How long has it been since the filter was changed?
Try the simple fixes first.Check oil level and for presence of water.If you have water,take all fluid out and replace. If you run bad fluid,when repairs start you will wonder just how much
fluid you could have bought for less money.Don't just let this "go" even if it does improve on its own.