i wouldnt fix it with sealant but ive seen it done before on ludes so its up to you. The o rings should only be a couple of quid for the 4, If u can use H22 ones then even better as someone will have spares kicking about.
Remove the broken bit of plastic from the pipe stick some selant around what left of the plastic elbow on the block and stick the breather hose back on and put the clip in place - surely you can do that
