I recently purchased a 290 yellow so I'm guessing an industrial model. Currently hydraulics are not working. I removed the filter from the bottom and it was covered in thick nasty slime. I am replacing the filter. I was also going to replace the hydraulic relief valve and took off the right side plate but I am not seeing the valve. According to the service manual it should be accessible through the right side plate but I don't see it. Any thoughts? Also, what causes that thick nasty slime to form. It was completely blocking the filter. I'm hoping that with a new filter I will have hydraulics and nothing else has been affected by the slime.