I had some custom programming performed on my shipping module for my Magento 1.4.X shop. Basically, I was having problems with customers putting a heavy item (or more than one) in their cart and the shipping option would show that the item could ship USPS First Class (or similar) which it could not. This obviously was costing me money in paying the additional shipping costs. To fix this issue, we assigned a weight per item and when the shipping options returned, it would only allow you to select an option based on the weight (Like USPS Priority or Parcel Select, but not First Class). This was working fine until the January 2014 USPS API update. The First Class option still returns correctly if the items don't way more than the First Class allows. If the items are too heavy for First Class, it returns this error:
This shipping method is currently unavailable. If you would like to ship using this shipping method, please contact us.
I need someone to patch the shipping API. I suspect it is just an issue with naming of the USPS shipping options verses what is coded in the shipping code.
I will only communicate with those who have Magento experience (and can prove such) and I will not pay upfront fees (been burned on that before).
Contact me with any questions.