I put this tip sheet together for a couple of reasons but mostly because the HP-41 is probably the most easily damaged calculator and many sellers (not collectors)

• exagerate the condition of their calculators
• don't disclose known flaws
• are unfamilar with what they are selling
• try to leverage off of other collectors auctions without providing the same quality calculator

There are many sellers that are also collectors. It is necessary that you know what to look for and what to ask. It is necessary that YOU be the judge. You must be able to tell a wholesaler from a collector. You must be informed.

There are two, far too common, problems with HP-41 calculators. One is broken screw posts and the other is corrosion.

Broken Screw Posts: The two halves of the HP-41 are held together by 4 screws that are screwed into posts in the upper half. The lower posts often break or get cracked. The top posts usually breaks on the lower half of the calculator. Result is poor contacts. This is easy to check simply by pulling the two halves apart. They should be tight, with absolutely no play. Be careful when tightening screws. Sometimes people glue case halves together, if these posts have been broken. This is a poor fix and you should ask if this has been done.

Corrosion on Battery Contacts: The other common problem is corrosion, on the battery contacts. Contacts should be bright and shiny. If there is any residue or dark areas, the contacts may have corroded. It is not enough to simply clean these visible contacts. If a 41 has had corrosion, however slight, there is a very good chance that the corrosion has migrated to other parts of the calculator. I would say that better than 50% of all HP-41s that I have come across have some form of corrosion. Beware of this or you too will have a pile of corroded calculators. I even had one person sell me a calculator that was sold as mint, that was full of corrosion. Be careful and ask any seller about potential corrosion problems.

Summary: Corrosion anywhere can lead to corrosion everywhere. You must specifically ask about corrosion. If corrosion has been removed, you must ask if there was corrosion on the inside and if that too was removed and neutralized. If there was ever corrosion and a seller says he doesn't know if it has reached the inside, you should assume it has.

Ask sellers if the case halves are held together tightly, without glue. This can be easily checked by gently pulling at the case halves and looking for any slack. NEVER overtighten screws, or you might break the posts.

Recommendation: Do NOT blindly believe everything that is in the text. Ask questions. Ask for more photos. If a calculator is Mint, Brand New, or Unused, it should be no different from one that just came off the assembly line. It is a lot easier to believe your own eyes. You run a risk when you pay high prices, for vintage electronics, from someone who is not knowlegable about what they are selling. There are many who are selling on eBay that are leveraging off of collector prices. Much of it is in non-working condition. Ask them if they are a collector.

Questions you should ask: (Be wary of vague or incomplete answers)

• Is(are) the photo(s) shown, actually, of the calculator being sold"
• Is the calculator 100% functional?
• Is there any sign of corrosion on the battery contacts?
• Are the case halves tight? Have you checked?
• Have the case halves been glued together, to fix broken posts?

Finally, even with all these precautions, you can sometimes still be fooled. But at least you have enough information to know what to look for and what to ask. Without photos, you have more risk and have to trust the seller's word. Check the feedback. Check for repeat customers.

.