I agree that a slightly different approach may be better, as you haven't made much progress.
Sometimes I will do as
@ycbm says but, if it now sealed into his mind that there is a problem area, I use a different approach. I would allow him to shy away from this area, then work hard wherever he feels OK. Then I invite them back to the scary area, to rest. So, they can go to the scary area and just stand. But, of they want to leave, that is good, we can go work hard elsewhere. When we dismount at the end of a session, that is also in the previously scary rest area.
I have used this for a number of horses. Soon, they want to go there.