bosch hammer sds gbh 2-18 re drill fault

i have a boschhammer sds and yesterday after using i struggled to release the drill bit that was in the chuck.
eventually got it out after 2 minutes of pulling at it.now it wont accept drill bits.they push in but will not lock in position.tried lubricating it but it does not appear to help.
is this a repairable chuck or time for a new drill.this one is 3 years old and is not used on a daily basis

Here's an exploded view of an SDS chuck - - the springs that control the ball bearings, have a habit of collecting rust between the coils, I have soaked these in WD40 or similar with exceptional results in the past. Find some way to seal the chuck whilst its held vertically upwards, in a vice or similar, fill the open mouth of the chuck (you may have to adjust the sealant) leave overnight. You may have to repeat this if you think the chucks still a bit sticky/catching and make it part of a regular maintenance, otherwise if the drills still good, replace the chuck...pinenot

Ive had this happen on my Bosch 36v SDS and also on my 110v Bosch SDS had to send them back to bosch under warranty and they said a sleeve needed replacing in the chuck.
The 36v is playing up again so im tempted to replace it with a nice new Milwaukee