What to do when buyer claims sellers item broken?

The buyer emailed me and said he already fixed the amps: $150 in parts + free labor. I will have to reimburse the buyer to make him happy with this transaction. I sold the Paraglows with Cobalt transformers, standard transformers, and AVVT 2A3 meshplates for $1325 shipped, net only $1286 after 3% Paypal. I spent $35 on shipping and now $150 for repair, so my net now total $1101. I should have kept the amps!
Link to my Paraglows photos:
http://photos.yahoo.com/bc/pt999/lst?.dir=/Paraglows+2A3&.view=t

Reply email from buyer:
"Thanks for taking the time to look into this problem. Your advice to
contact a competent technician was good. I have been working with electronics for the past 20+ years first teaching and for the past ten years I have been repairing medical lasers.

I was very careful to install the 2A3 tubes with the large cathode pins in the proper holes. After taking the time to examine the amps, I found several problems. On one amp, the 2A3 cathode resistor was open causing excessive voltage across the bypass cap causing it to breakdown. This was the cause of the popping noises.

On the other amp, this same resistor was a high value, 7K versus a
nominal 3K.

I have repaired them both at a cost of about $150 in parts. I used some premium parts but do not feel this is inappropriate. This does not count the cost of my time. I spent the better part of a day repairing them. I do not think it would be possible to get them repaired at this price from a repair shop.

Given what I know about electronics and the condition of these amps, I find it hard to believe that both of these amps were in good condition when they left you. However, I am willing to give you the benefit of the doubt provided you cover my costs for parts. I will throw in the cost of my labor at no charge. You can send it back via Paypal if you wish."

...it seems like the primary reason on defected cathode resistors were bad tubes i.e. old and the amp needed re-tubing real urgent...

Always make clear that the sale is "as is, where is." That is to say, the buyer either takes your word for the condition it is in or s/he can come verify it personally, but you're not going to hassle with him/her if it isn't what s/he expected. Now, to be ethical, this means that you must be VERY careful that you accurately describe the equipment and its current level of performance. The second thing it means is that if the equipment is damaged in shipping that is entirely a matter between the buyer and the carrier. Again, you must be very clear about how you are going to package and ship but it is up to the buyer to tell you if that isn't satisfactory.

I get the signature of the buyer on an "as is, where is" statement before I accept the money and/or ship the merchandise. Sure avoids a lot of problems.

In the present instance it sounds a bit like the buyer wanted a component upgrade and figured you might as well pay for it. I could be wrong, of course.

will

By the way:
Did the buyer send you or faxed you or e-mailed you the parts invoices that he spent the money for?
His responce as from the technical point of view seems to look like a responce from a confident person on that issue, but anywhay it needs to be checked for the "gipsy transaction". Being confident sometimes gives you a power to argue and flirt even if there is nothing to argue about and YOU are in the situation that you have to trust to what the buyer sais(pretty odd isn't it?)

Further on to avoid such situations follow Will's advice firmly.

After thinking about the situation for a day, I finally emailed my buyer offering to pay for the standard parts replacements costs or a refund if he sends the amps back to me in its original conditions. Attached is my email reply:

"I'm glad to find out that you are the competent technician for the repair job.

From what I understand, on one amp a resistor is open, on the other, the resistor was of wrong value. So the fix is to solder the open resistor on one amp and replace the wrong value resistor in the other. I can understand that the shipping process can cause a soldier joint to come loose causing the popping noise. I bought these amps preassembled, the wrong resistor can only happened at two places, either Doc B. put the wrong value in the kit when he shipped it out, or the previous technicians error in assembly.

As for the parts upgrade, I find that it is not fair to ask me to pay for the upgrades in place of the originals. It is fair to pay for the standard parts replacements as Doc B. would have included in his kit.

Used equipments are sold as is, that's why they are advertised as used, and the buyers save money buying them used, at the risks of no long term warranty or support. I do my best to describe my used equipment and provide the buyers with plenty of photos to describe its conditions as well as packaging. During my 2 years of using the Paraglows, I have not noticed obvious popping noises or any other side effects. If you think these amps are not in good conditions when I sold them to you, you can packed them up and send them back to me tomorrow in its original conditions for a refund."
PT