Wobbly bricks

[dancemonkeydance]

Basically, I've taken an interior wall back to brick because the original render was incredibly dry and was no longer adhering to it.
Underneath the window are a few loose bricks and there is very slight movement in the brick work. The mortar is very dry and quite sandy.

Is there anything I can use on these bricks to stiffen them up? My plan was to plaster some cement slurry on before bonding.
If I start taking bricks out to re-bed them, I worry i may end up down a rabbit hole.

 

[foxhole]

Gently rake out and re-point , a cement render would help before plastering. [with mesh if it's really flaky]

 

[Jackrae]

I've found a 10:1 water PVA mix 'painted" on very good at stabilising loose old plaster edges and surfaces before doing any cover or filling work.