Apply grease to the following points once every 3 months as
a standard. Also, note that RUBBER RING 70 is not of an oil-resistant
type and is susceptible to a quality deterioration if oil attaches.
Make sure that grease and any other type of oil do not adhere
to it.
Once every 6 months as a standard, check to see if any damage
is caused to the rubber stoppers. If they are damaged, replace
them with the spare parts in the procedure shown in the FIG. below.