I have the same problem ... It used to be good but now it seems that all the public proxies die very fast!
I downloaded the piznProxyProcessor from here and just did a test run, got about 500 good proxies after testing, but when i use them in Scrapebox i can't harvest.
So i decided to do a test on those proxies in scrapebox and i got only 8 good ones out of 500 ....
What is wrong? Got a lot of errors: 301,404,404,ip blocked ...
cricket1: can you give us a hint how to use different footprints in SB to find fresh urls for proxies.