- suggestion 11241-EVS is not a breaker hammer but a rotary hammer but has almost the same good quality as a breaker hammer because its a reasonable solid product with a liquid lubrication.
Solvent clean the front drill and chisel holder in the spindle thoroughly to control before buying a maintenance parts kit , decision to take the step ONLY IF............ the spindle (most expensive part) is smooth has no rips or is worn but first inpriority check in advance whether the three SDS driving lanes for the bit internal closure and drill -drive of the drive spindle =pos 25 in the drawing is still be adequate enough a 1.5 mm and round tops is critical. and below that its not worth to repair. because the working hours on it have been achieved.
Otherwise If its looked like the 3 lanes inside the spindle all three are always the same size about 2.5 mm thick and are square topped the spindle (and the other parts are must have to be in good condition to service. buy the maintenance kit its in the drawing to find in the parts list pos 897 and oil partslist pos (898 or 895) for if you have more then one rotary hammer to service.
Most cause its conclusive for only this parts but a priority is to replace ALL pieces of the service parts. even the carbon brushes
look that after replace the green ring on pos 856 that this hammer piston connecting rod is correct mounted on the right side again with the 4 little stips on the (bearing) outside thats coming downsite on the eccentric cog wheel for a smooth working for the plastic plain bearing on the metal connecting rod, At the slightest mistake in the parts and lubrication breaks this connecting rod soon.
The striker pin has great priority to clean and control that part against leaking a retainer ring should be removed by use 1 or 2 little screw driver(s) in the small holes on the side of the spindle can be seen this ring. if the ring comes loose tilt the ring cross with a long screwdriver pull it out with a nose pliers. to get the (striker pin or impact bold (the part thats beat the chisel )by other brands named the special ring has exterior little orings inside becarefull and look first inspected how its build before there will one come out to push it again inside if one will come out.
There is also a new retainer ring for the parts around the striker pin in the delivered maintenace kit
By replace the several parts beware on one ring not to forget a very important ring pos 104 to replace it and mount it with some sillicon grease in the right groove before in order to prevent a disappointment of leaking oil because if leaking oil /air after a while the parts will dried out in a very short time and will burned out soon.
There is one problem rised between me and this kind of BOSCH powertools about the ring(s) in pos 102 there are 2 shim (bearing) rings pos 102 to find by the service handling and what you will know from me is that you must look that there are two shims to find instead of one because of to get a correct backlash measure between 0.08 and 0.22 that's the right tolerance to adjust the shim bearing rings to have some tools ONLY to know how to handle if they are forget the second shim ring in your model if you are going to make service if you only have one shim ring because there where failures in the drawing by Bosch on this and to find more about the use in some other comparable bosch models like gbh4-32dfr or 4-40de that will have in order to adapt the backlash adjusting have a failure if only one ring is used.
More on fixya to find about the pos 102 position rings by Bosch in several models.
Hoping that YOU HAVE 2 rings of pos 102 you have nothing to do to concern on let it be as it is. only if one ring you should hear the difference in rotary position , it should not be turn smooth.
But if one shim ring is used only like in the drawing it must be a factory drawing failure.
look on the partslist by the model you have it shows there are 2 different rings to buy or order of the same pos 102 for it they sell you can buy if you do not believe on my story its so imortant to adjust the gears for the backlash if only one ring is in this machine you will have to order 4 new pieces 2 of the 2 neccesary to adjust know to make the backlash rather on 0,08 mm then 0,22 mm as soon you have adjust because otherwise the machine will make the rotary gear worn in a to short time.
If its has only one shim ring and its have making already a very bad noise in the rotary drive position replace only if its worth all to gether to service also pos 51 and pos 860
Bosch 11241EVS 0611241739 Rotary Hammer Parts