I have a 2013 Super Bee 1-K that has developed a knock in the hydraulic system. It has the load cushion feature and is joy stick controlled. It has less than 300 hrs. There is no visible leak and it is not losing fluid per visible check or monitoring the site gauge. I have drained and refiled the system, replaced the main filter and inspected the in tank filter. On a side note I have been unable to source the in tank filter and don’t want to go through NMC if possible. Any ideas as what to look for? Pump, back flow valve, faulty valve?Any advice would be greatly appreciated.