MonkeyRunner NoClassDefFoundError: com/android/chimpchat/ChimpChat

Shortly after posting the comment, I figured it out. After fixing the Chimp issue, there were more libraries that Monkeyrunner was not able to find. In the end, it seemed easier to do the following:

You probably have your $ANDROID_SWT set to something like sdk_dir\tools\lib\x86_64. Copy your ANDROID_SWT\swt.jar into sdk_dir\tools\lib and then set $ANDROID_SWT to sdk_dir\tools\lib.

After I fixed this issue, I had problems with Monkeyrunner not finding adb. For that, I had to replace the last line in monkeyrunner.bat from

call "%java_exe%" -Xmx512m "-Djava.ext.dirs=%frameworkdir%;%swt_path%" -Dcom.android.monkeyrunner.bindir=..\framework -jar %jarpath% %*

to

call "%java_exe%" -Xmx512m "-Djava.ext.dirs=%frameworkdir%;%swt_path%" -Dcom.android.monkeyrunner.bindir=..\..\platform-tools -jar %jarpath% %*

Basically, make sure that -Dcom.android.monkeyrunner.bindir points to where adb.exe is sitting. Now it seems to be working.