Oven repair advice needed

[Steellearning]

This year I found that I needed some shelter for my oven and during the build we dropped a 6 meter 4 x 12 on the ovens entrance which didn't go so well. If you look at the photos you can see that I have removed all the bricks that were loose but there are some left that have a few cracks in the mortar joints. The bricks don't seem to be loose so my hope would be to just remove some of the mortar in joints that are cracked and refill these with some home-brew?
I also have some cracks in the rear also that i thought I would repair in the same way while I'm at it? These are expansion cracks not caused by the 4 x 12.
Whats the best way to remove mortar from the cracked joints without creating more damage? I was thinking using a Dremel or Bosch multi tool.
Any advice will be greatly appreciated.

[david s]

Yes use a power tool. Avoid hammer and chisel. I presume you have the original bricks to replace.. Try to keep the whole area damp for a week after the repair. I'd be using some wet burlap or sacks. If your brick work is totally dry ( had you already driven out the water?) get it moist but not wet, again before doing the repair.
Good luck.

[Steellearning]

Thanks David..
I cleaned up the arch bricks and I'll mortar those in place before I clean up the openings for bricks over the arch. I feel the arch will give me some more support so I don't cause any more damage while cleaning up the rest of the joints.

[william]

I think I would burn the offending 4 x12

[Steellearning]

I've repaired the damage caused by the offending 4 x 12 and the oven works great. Still have some small cracks but there doesn't seem to be any smoke leaking through so i'm not going to worry about it.
I widened the chimney flue gallery while I was at it and made a flue gallery cap using homebrew 1 1 1 3. The steel chimney pipe is 8 inch as recommended and I now have zero smoke coming out of the front of the oven. I'm very pleased.
Thanks for all the great advice David.