Then what I did....and I think this step is very important.....is to install some servo bearing blocks.. I used spruce I think... or any kind of hardwood, about 5/16" or so... enough for that servo mounting screw to bite into. Make them long enough to capture fully, so as to "pinch" the hole mounting into existing, as well as the plate that you added. I used 5min epoxy here, as once this step is done... I really don't think the servos are going anywhere. Again,,,this in my opinion is the most important step... your whole servo install is only as strong as the weakest link, and this shores the whole thing up....