Just a suggestion - why not clip a seperate sling into each hanger and extend them for your tie in point instead of clipping directly into the webbing? It would put less force on the bolts and also takes the existing webbing out of the equation (one less thing that could fail).
An application can be made directly to the park (without having to go through the Fixed Hardware Review Committee procedures) to upgrade rappel anchors and bolts with modern hardware.
I don't own a drill or have the expertise to do the job right, but I'd be glad to help someone who does.
I've never done the climb. I have never stood at this spot. but, at the same time it looks like those cracks to the left of the picture could take gear. Are they flaring? On loose blocks? Why clip that tat at all?
Mike, I tried that but I could not get a 'biner through the old hanger due to the space the slings were taking up. Chains would help solve the problem, but I would be in favor of a new anchor per Dave's suggestion.
Phil, the "cracks" are loose flakes. Probably the only reason they are still there is fear of killing a bystander at the cliff base if you pry them off.