That callous you are developing on the back of your arm could be from propping up the lid of a C2463/2564/2453/2553 printer cover. If your feminine office staff, goes from demure to demented, this could be the cause. Those gas shocks, that keep the lid up, wear down and aren't up to the task. The replacement part will usually go for $33. At www.hptraderonline.com our new replacement is only $18.00. If your in need, search for "shock" and there you are. Click "Replacement" for a picture. Guy Avenell Sales Manager