The E-61 group has been around for over fifty years and for good reason. It is simple to work on and it makes great espresso for a lot of reasons. But that's not why we are here. I am going to detail the steps it takes to overhaul an E-61 group.
      Be aware that there are some difference between manufacturers when it comes to this group so yours may not look exactly like this one. I am showing the manual (lever) group from the Vibiemme Domobar line. If your has an electrical activation for brewing then there will be differences which you will have to investigate before beginning. On the other hand, for the manual group, internally the general layout is the same regardless of the brand. I suggest getting a parts breakdown for your group before beginning to disassemble your machine, and compare the parts as shown on your diagram to what you read here.
      If your group needs more attention than just a simple lubrication, check out the sister article I wrote, Overhauling and Lubricating the E-61 Group.
      But before you begin, if the lever feels rough when moved it could be caused by friction between the external cam on the lever and the switch that activates the brew cycle. You can put a drop of lubricant on the cam where it contacts the switch then operate the lever through its range of motion a few times. If that solves the problem then there is no need to go further. If after aplying the lubricant the lever still feels abnormally stiff or rough, following the instructions below will likely be necessary.

PREPARATION

TOOLS
      Most E-61 groups can be completely disassembled some simple tools:

REMOVAL of OPERATING LEVER ASSEMBLY
1		Move the lever to the "middle" position. To find that, move the lever upwards towards the brew position until the first resistance is felt.
2		Remove the nut or screw that holds the lever to the shaft. Remove the operating lever from the shaft (not shown). Loosen the outer nut (shown here). Skip this step if all you are doing is a simple lubrication of the cam. Remove the two socket head bolts (or the larger, inner hex bolt if your machine is so equipped). Pull the entire lever assembly straight out. You may need to slide the lever back onto the shaft and give the shaft a wiggle back and forth to get the assembly to slide out. NOTE: At this point, if the lever is operating smoothly and all you want to do is lubricate the cam and related related area, skip to step #11
Operating Lever Disassembly
3	Unscrew the outer nut (which you loosened earlier on) and remove the spring and bushing from the shaft. The shaft can now be pulled out from the cam end.
4		Inside the larger lever body you will find two rubber washer seals. You can see the division between them in this photo.
5		If you have a dental pick or any similar tool which isn't too pointed or sharp, you can use it to get between the two washers and pull the outer one out first (I used the tip of these tweezers). Repeat to get the inner seal out. These are identical, by the way. Use care not to score the inner wall of the housing.
Lever Assembly and Installation
Here are all the parts of the lever assembly and the order in which they fit. Note the orientation of the bushing and the spring's location.
6	Install the two shaft seals into the lever housing. Use a cotton swab with one of the cotton buds broken off as an applicator, and apply a coat of silicone on the surface of the seals' bore where the lever will go through. Also lubricate the shaft portion of the of the cam's shaft with a very thin coat, rubbed well onto the surface.
7	Slide the shaft into the housing and slide it through the seals, in the direction shown in the above photo.
8	Drop the bushing over the shaft, wide portion first.
9	Slide the spring over the bushing.
10	Install and hand-tighten the retaining nut.
11		Before installing the lever assembly, use the cotton swab's stick again and place a SMALL dab of silicone on the flat end of each of the valves when they protrude into the cam's chamber (indicated by the red arrow and the green arrow). Also distribute a dab into the hole in the center of the far-side of the cam chamber where the end of the shaft will rest (the area indicated by the yellow arrow). You can also put a thin coat on the cam's operational surface as well
12		Align the cam so that it is towards the front of the machine as shown here.
13	Slide the assembly into the group. If it does not seat, do not force it, Gently wiggle it a bit and it will go in once the cam is in the correct position. Screw in the socket-head bolts (or the large hex on the housing) by hand and tighten, then tighten the outer nut. If your assembly screws into the group, put the lever onto the shaft temporarily and use it the push and turn the shaft to get the cam into place.
14	Slide the lever handle onto the shaft, aligning the lever so that it points at about 8:30 (the "middle " position of the lever when in operation) when looking at the lever-side of the machine. Operate the lever to assure that it moves smoothly and extends to the upper and lower positions correctly. Install and tighten the screw or nut that holds the lever in place.
15	Turn the water back on if necessary, then plug the machine back in. Turn the machine on and lift the brew lever to the brew position and flush some water through. Insert a blind filter in a portafilter and do a few clear-water backflushes to check for leaks.
16	If everything looks good, allow the machine to heat up and do a few more blind backflushes to help clean out any stray lubricant.
Time To Make Some Espresso!

Ya, I should have played with the white balance, but until Spielberg calls, (that's Helen Spielberg who runs the Kosher deli in town), I'm not going to worry about it.