Z axis feedrate issue

Using Slic3r with Pronterface.

All of a sudden(last two weeks), the Z axis feedrate cannot be controlled.
I have been using a Z axis retract for months without problem. Z will overshooting the target and end up scrapping the bed. I have to manually add a Z axis feedrate for all Z axis moves for Z to operate correctly. I know I changed some setting somewhere but I am unable to find out what I need to do to fix it.
I have tried the following without success

#define DEFAULT_MAX_FEEDRATE {300, 300, 10, 1000} // (mm/sec)
#define DEFAULT_MAX_ACCELERATION {500,500,200,1000}

I have tried the M500.

No matter what I try or change the Z axis screams up and down until I manually add a Z axis feedrate to all Z axis moves in the part part program.

Help.

I don't quite understand the problem. The term retraction is usually used to refer to the E axis. I think it sounds like your Z speed is too high?

The actual speed at which the head travels is determined by the slicer, but the firmware settings can impose lower limits if your printer can't attain that speed. Normally when the speeds are wrong, it is a slicer setting that is wrong.

When you say you enter a Z axis feedrate, what exactly are you doing? Are you typing a manual command into pronterface? If so, what is the exact command.

`#define DEFAULT_MAX_FEEDRATE {300, 300, 10, 1000} // (mm/sec)` is basically what goes into the source code, not in the same place where g(/m)-codes are sent. It is compiled and then fed into the chip when programming it.

I think z-retraction is done sometimes too,(not sure if it is necessarily a good thing) i dont see a lift speed in slic3rs options. Could set `--retract-lift 0`. (or `retract_life = 0` in the configuration file) In linux the configuration file should be in `~/.slic3r.cfg`(well, the default; `~/.Slic3r/slic3r.ini` determines which) dont know for windows, look for it. (Note: I only just found out this existed, i used a little shellscript to do exactly what i talk about now does; `$SLICER_BIN_DIR/slic3r --load ~/.slic3r.cfg $@` i also use it to remember for me what arguments i used before and output in earlier occasions.)

Note: would be handy if there was a html version of slic3rs --help output..

I just know found out that when I uncheck "Retract on layer change:" in Printer Settings in Slic3r the problem went away. Using the Crimson Editor I would add "F100.0" to the gcode line "G1 Z0.250" to make "G1 Z0.250 F100.0". Each Z axis command in the gcode is appended to prevent the overshoot. I don't understand why "Retract on layer change:" is affecting the Z axis feedrate. I am happy I can print again.

I dont understand it either. Tried feeding the reprap gcode from cura once and it went crazy on that one too..