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I have heard that a m'zuza must be checked twice every seven years by a qualified sofer. I have also heard that, assuming it's known to have been kosher at one point, it need only be checked for faded or cracked letters thereafter, and that that check can be done even by a layman who knows what the letters look like (provided he take any questionable m'zuza to a sofer for expert checking). Which is correct? Sources please.

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Which skills will a qualified sofer use except his knowledge of what the letters look like? – Double AA Jan 17 '13 at 17:46
@DoubleAA, perhaps things like how much fading is acceptable vs. a problem, how much of a change constitutes a crack (naked eye? magnifying glass?), etc. – Monica Cellio Jan 17 '13 at 17:50
@MonicaCellio yes, though (as I'll edit into the question) someone unsure would then take the m'zuza to a sofer. – msh210 Jan 17 '13 at 18:43
If he's qualified enough to never kasher a posul one, what could be the problem? – Double AA Jan 17 '13 at 20:27
@DoubleAA, what could be? I don't know. One possibility, I suppose, is a rule that only someone with the safrus equivalent of sh'chita's kabala can check m'zuzos. Beats me. – msh210 Jan 18 '13 at 3:14

I am a certified sofer. I will tell you my opinion. First I would like to ask you to take a look at my website, particularly at my blog, Diary of a Sofer. I have digital pictures of many shailos that come up. Most days I see shailos, either in mezuzos, tefillin, or where mezuzos are put. Many of the shailos are in mezuzos that have been checked. Sometimes people have missed some pretty incredible things, as you will see if you follow my blog. If you have high quality mezuzos, and those mezuzos have been computer scanned, and they have been checked by a certified sofer, and you don't have any special problems with the writing, it is possible that you may do a fine job. There are two problems however, that I see. One, you may not know keses hasofer, and mishna berura on these inyonim. There are some central halachos that you need to know before you work with mezuzos, or you can end up posseling something, and never knowing it. If you are never planing on touching a knife or a pen, you certainly have less chance of messing up, but I couldn't recommend it unless you were familiar with the main halachos of stam. I don't mean you have to take a test on the halachos of how to make dio, but you should know what chok tochoks, sho ksidran, kiddush Hashem, mukaf gvil, and leshma are. I just can't believe that without knowing the basics of those halachos that mistakes won't be made. My website is mezuzadepot.com and you will see many shailos there.

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Did this advertisement answer the question at all? – Curiouser Jan 23 '13 at 3:33
I think he's saying that an average person would probably do ok checking them himself if he at least knows the certain rules he listed. I have no idea though how knowing what shelo kisidran, kiddush hashem, chok tochos or leshma are will help one check. Mukaf gevil I accept you should know, but it's pretty straightforward. – Double AA Jan 23 '13 at 4:21
Certainly much of the advertising should be removed, as well as the extended discussion about the many many mistakes he finds in checked mezuzot which you can read about elsewhere, which does little more than try and scare a new checker without any precise basis. – Double AA Jan 23 '13 at 4:23
@DoubleAA I don't see how mukaf g'vil is necessary knowledge, considering that an assumption in the question is that the m'zuza was once valid. – msh210 Jan 23 '13 at 5:04
@msh210 If a letter touches the edge of the klaf because the paint expands (say through heat) then it needs to be separated before use because of mukaf gvil. (There's also related rules about big and small holes in the klaf and letters touching each other.) – Double AA Jan 23 '13 at 5:07

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