The 2SK1237 N-channel transistor is the subject of this 45.8 KB PDF, filed under the schematic category. The 2SK prefix places it in the JIS numbering of N-channel field-effect transistors from Japanese makers. Contents are likely a ratings table, electrical characteristics and a package outline with pinout. Use it to locate gate, drain and source for meter testing, to confirm proper orientation when refitting, and to select an equivalent if the original part cannot be sourced.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @cyberlanelectonik. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.