PSA Cert #:40814458
1957 Topps #302 Sandy Koufax PSA 7 to PSA 8 
Alteration types: Corners sharpened
Set Registry status: In a user's private Registry
Sold on 3/14/2017 as a PSA 7 by PWCC to whitman111 (Gary Moser's eBay ID) for $559.00
Consigned to PWCC and sold on 8/13/2018 as a PSA 8 for $1,381.00
Final price: $1,381.00
Value gain: $822.00
  
This card was purchased from PWCC by Gary Moser's whitman111 eBay ID as a PSA 7 and was later sold again as an altered PSA 8 by PWCC.  The bottom two corners were sharpened by the card doctor, as you can see in the images below.  This alteration is especially apparent when looking at the lower right reverse corner, of which I included a detailed image.  I believe that a combination of soaking, pressing, and then filing the corners to a sharper point was used to turn this PSA 7 into a PSA 8.  This same method was likely used in the alteration of a 1957 Topps Mantle/Berra card, which was also purchased by Moser's whitman111 ID prior to doctoring (see 
Post #6068 here).  Regardless of the method, it is 100% altered.  Green circles show print spots and/or paper fibers confirming the two sets of images are of the same card.  Pink boxes highlight the altered corners.
PSA 7: 
https://www.pwccmarketplace.com/items/1446976
PSA 8: 
https://www.pwccmarketplace.com/items/1721409
