Geothermal loop replacement costs eligible for tax credit?

We had a geothermal system (closed loop; vertical) installed for our house (new construction) in 2009 and claimed the 30% tax credit for the eligible costs. Unfortunately, we have had chronic issued with the loop field since then (long story involving shoddy work by the well driller) and ended up having to replace one of the five loops in the field. My question is whether the cost of replacing the loop might be eligible for the 30% tax credit. I have found some discussion regarding the cost of replacing/upgrading an existing geothermal unit (consensus seems to be that these expenditures should be eligible for the tax credit), but I have not come across any discussion regarding repair/replacement costs related to an existing geothermal loop. Seems like a grey area to me - curious whether anyone has thoughts/opinions about this. Thanks.