how to clean wheel sensors??

[opihiman911]

My roomba discovery se started doing the spin and 4 beeps. Reading other posts in here I figured it is a dirty wheel sensor that needs to be cleaned.
How do I remove the wheel to clean them? There are 3 small screws on the outside of the wheel. I can remove the top 2 screws, but the third one in hidden under the plastic body?
Any help appreciated.

Thank You,
Cory

[Gordon]

...How do I remove the wheel to clean them? There are 3 small screws on the outside of the wheel. ...

Actually, there are FOUR to remove!
1) You need to take off the Bumper and top Cover. Read Accessing Discovery's Interior, to see how to do those operations safely.
2) Then you can visit RoombaHelp to get some visualization of what it takes to get a wheel clear of the chassis. Try to avoid the temptation to drill holes in your SE! At that site, there will be a picture of a "cleaned" detector (or LED), but it is not very clear, so...
3) Take a look at this picture,

to see what a cleaned lens looks like. The lens is the circular item in the slot between the rectangular blocks.

When cleaning these lenses, I like to use a tiny (#2, camel's hair) art-brush, with bristle-length trimmed to about 2-mm. The brush is then wet with isopropyl alcohol and used to flush away all dirt, on and around each of the two lenses (per wheel).