Where is Water tank on 2011 3060

We just purchased a new to us 2011 3060 Windows Express and the water tank gauge isn’t working.  We were advised to check the float but how do you access the tank in order to get to the float?  We heard that it’s possible that the float is gunked up and needs cleaning, but we have searched the manual and just cannot find where it’s located.

Thanks in advance (and if you have any other advice on what to check, I would appreciate it).