Boots, Decompr.

Rubber items like these tend to degrade over the years, through general wear and tear and of course U.V exposure, so take the opportunity when refurbishing the control levers to replace these at the same time.
You may wish to consider these related parts:

53176MG3641
53177MG2000

If this item requires replacing it is likely other rubber protective items will also require close examination!

To access the list of all the parts required to complete a control lever makeover, take a look at the online schematic for your model. You can then order all the parts required in one hit and save money on shipping costs.