Trust me, the temptation is there! But not to get political; "affordable healthcare" just took a substantial dent out of my disposable income. If somehow I can come up with around 10K from some side work, I may go with the overhaul and lower the pond level and expand to capture springs. It may mean starting over fish-wise, but it may be worth it.
Do you have any pictures of the site? I guess I'm not understanding, is the water seeping into a spring under the pond or can you see where the water is seeping through the dam? I think overhaul would be the cheap route and maybe they might break the spring that is sucking the water out of your pond if thats the case.
