Hi: This reliable calculator is a gift that served me well for over 20 years with the Math 1 and Advantage modules. 4 Type N batteries; Serial No. 2338S42235.
Low Bat indicator never lit. Problem noticed when Ex Alpha Matrix Function used: Prompts order; I enter 2, 3, & 4. Display always ORDER=5\/ TVM Function (compound interest) OK. I lost manuels but have the user guide. Can't set time, date etc. {Later I foolishly tried clearing Reg & Stack. etc} Cat. #3 still showed the apps. "Invalid Entry" was a typical response for all Alpha cmds. Later, unable to store intermediate calc via: STO 00,01,02... Regular Calc. operated OK then.
Removed battery pack to "reset things." Blank display after installing 30 sec later. Cleaned contacts; found cells were 1.2 V each - why no lo bat indicator? Before I get 4 new ones, how messed up is the data structure? I likely made it worse, but had to get Cramer's rule working. Sorry if this is long. Dan. ICT, KS.