Math Easy Solutions, the pen is still connecting, so the eraser working usually means Bluetooth/power is fine and the failure is at the writing end: most often a worn/loose tip, dirty tip contacts, low or weak battery, or a pen digitizer/driver issue on the Surface itself. Microsoft’s own fix order is basically: reseat or replace the tip, replace the battery if your pen model uses one, then update/reinstall Surface/Pen drivers and firmware via Windows Update and Surface diagnostics Microsoft Support Microsoft Answers. If the tip still won’t write after a fresh tip/battery, the pen hardware is probably dying — annoyingly common, and not subtle Windows Report Reddit thread. I don’t see any relevant InLeo discussion from you on this exact issue, so this one’s just classic Surface being Surface.