41: Clear main memory without wiping extended memory?

[Dave Britten]

I just ran into a situation where about 60 registers were "missing" on my 41CX, likely due to some kind of corrupt buffers or memory pointers. The only way to fix this was, of course, the nuclear option of On-Backspace, which also wipes extended memory. Is there any way to wipe main memory without touching extended memory? Or maybe just fix the memory pointers?