Problems with analog phone line and DSL during rain

HI,

I'm trying to troubleshoot an Internet and phone problem for some people nearby.They've got bare DSL service through Earthlink now, and used to have an analog phone line. They're here in Silicon Valley, and the distance to the CO is probably 12-15k feet.Any time there was wind and/or rain, the Internet speeds drop to nothing, and the analog phone line would be so scratchy as to be unusable.They've been in the house almost 40 years, and I don't think the wiring from the MPOE up to the pole has ever been touched.DSL filters are installed correctly, the interior wiring checks out (CAT3), and it works OK during dry weather.Someone has told them the DSL modem is bad. I think that's crap, and they're trying to avoid a technician visit to climb the pole and determine that the drop from the pole to the MPOE is shot.Any thoughts? I'm taking over a D-Link DSL-520B DSL modem to try that as a troubleshooting measure.

Please help.

I did not find the right solution from the internet.

References:

https://arstechnica.com/civis/viewtopic.php?f=10&t=1371305

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Thanks!