Anybody have an idea how to fix my beloved 11C? (Actually, my beloved's beloved 11C; I have a 15C.) Here's the scoop:

1. Calculator turns on by pressing any of these keys: ON, f, g, STO, RCL.

2. When f is pushed with calculator on, "f" does not appear in the display. None of the f functions work, i.e., I cannot change from SCI to ENG. "g", however, does appear in the display when g is pressed, and g functions correctly, i.e., I can change RAD to GRAD.

3. No multi-digit number can be entered. If you try to enter 45, first 4.0000 will appear, then 5.0000 will appear.

4. All functions seem to be working, meaning multiplication, addition, subtraction, CHS, exp(x), sin, and so on.

Calculator fails the +, x, / tests with Error 9.

Thanks for any advice!