replacement for flat bench flies?

A couple of years ago I dislocated my right ulna doing flat bench flies and spent a few months in physio to get the bone back in its socket. I think a tendon in that arm (the one right under the elbow) isn't fully attached any more.

Anyhoo, I'm back to working out. After two months I have concluded that I can't do flat bench flies any more. I'm getting serious guarding when I extend my arm and as a result I'm messing up my right shoulder during those reps.

Any ideas on an exercise to replace it, or is that really necessary? I work out at home and have an incline/decline bench. Cable flies work great but I'm not ready to buy a cable system just for 1 exercise.

Currently my chest exercises consist of:
- bench press
- flat bench flies
- dumbbell press
- incline flies (which don't give me anywhere near the problem)

I was thinking of dropping the flat bench flies and adding a decline dumbbell press.

Suggestions would be most appreciated.