I’m good at the following:

1) Removing and replacing the original battery cells

2) The case is NOT split, so the unit fits perfectly back in your calculator

3) I use 1/3 AAA NiMH cells which are a little smaller than the originals but work well.

I’m not good at the following:

1)      Rebuilding the internal IC circuits if corroded 

2)      Overcoming extensive battery clip corrosion.  They have to be "springy" to function

Shipping is at your cost and is generally $4 inside the USA and often $15 for international customers.  

 I will guarantee my repair for 90 days, and if it seems unfair to you how I fixed it,  I will refund your $50 via PayPal, but I need to see pictures and explanations of what went wrong and how it is not operating as you want.  I need to learn too if I made a mistake.  I will re-fix it for you if you want for only shipping costs. 

 I have other auctions for HP calculators: Different battery packs, Orings and instructions, USB charging cables and Stand-alone charging boxes  if you search on Ebay for waterhosko