revert broken links

_gcode/M207.md

@@ -47,14 +47,3 @@ parameters:
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 Use this command to set various parameters for firmware-based retraction. Send `M207` with no parameters to get the current firmware-based retraction settings.
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-### Retract/Recover tuning
-
-Calibrating retract/recover lengths and speeds can be challenging because it requires just the right balance of 4 parameters. Fortunately you can print this simple test pattern by JCZD with only a little bit of filament:
-
-![retract-recover helper](//engrnage.ch/files/marlin_retract_recover_helper.png)
-
-* [3x3x3x3 pattern](//engrnage.ch/files/retract_recover_3x3x3x3-jczd.gcode) - 81 individual samples, you probably want to start with this and it should give you a decent approximation
-* [4x4x4x4 pattern](//engrnage.ch/files/retract_recover_3x3x3x3-jczd.gcode) - 256 individual samples, for fine-tuning
-
-These G-codes should work for bed sizes 300x300mm and smaller. A customizer is under construction, but in the meantime you can use search-and-replace. These G-code files **must be modified** to work on your printer. Read the comments in the header and the first few lines and update the indicated values for your machine and material.