Here are some pictures and descriptions of the parts for your convenience.
Delta Model # RP25513 available at Home Depot for only $13.26 each:
Link: <a href="http://www.amazon.com/gp/product/B001D0N63Y/ref=as_li_qf_sp_asin_tl?ie=UTF8&camp=1789&creative =9325&creativeASIN=B001D0N63Y&linkCode=as2&tag=aff iliatechie-20">Delta Faucet RP25513 Stem Assembly</a><img src="http://www.assoc-amazon.com/e/ir?t=affiliatechie-20&l=as2&o=1&a=B001D0N63Y" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" />
Here are the Seat and Springs by Danco (fits Delta) Model # 86968 Tom is speaking of also available at Home Depot for only $1.97 each:
Link: <a href="http://www.amazon.com/gp/product/B000DZDRHU/ref=as_li_qf_sp_asin_tl?ie=UTF8&camp=1789&creative =9325&creativeASIN=B000DZDRHU&linkCode=as2&tag=aff iliatechie-20">Danco 86968 Delta Faucet Repair Kit, Delta Seat-Springs</a><img src="http://www.assoc-amazon.com/e/ir?t=affiliatechie-20&l=as2&o=1&a=B000DZDRHU" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" />
Here is the O-Ring seal 3-Pack that may be all some lucky people need if the cartridges are not damaged by Delta Model # RP2055 for only $5.99:
Link: <a href="http://www.amazon.com/gp/product/B0009VP4PQ/ref=as_li_qf_sp_asin_tl?ie=UTF8&camp=1789&creative =9325&creativeASIN=B0009VP4PQ&linkCode=as2&tag=aff iliatechie-20">Delta Faucet RP2055 Spout O-Rings, 2- Pack</a><img src="http://www.assoc-amazon.com/e/ir?t=affiliatechie-20&l=as2&o=1&a=B0009VP4PQ" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" />
For the money it wouldn't be all that much just to change out the cartridges like Tom has done. It is a pretty straight forward job. Delta makes things pretty darn simple. My plumbing buddy swears by them. He will repack a customers Delta kitchen sink faucet for $175.00 and his cost is pennies.
I went ahead and corrected the thread title for everyone. Eventually this thread may have to be split up for both Grohe and Delta