Led is very dim and i have no schematic .
Gee, that's an oldie from the early 1980s. I've got one that exhibits the same traits. Not much you can do except send it out for a repair estimate. Since you are asking and you have no schematic, apparently you are not up to troubleshooting the unit. I see where the Pikeville Law Enforcement and EMS are still UHF so that scanner will pick them up. Does the scanner still receive well? That might be a deciding factor in whether or not to seek out a repair estimate.
BTW, welcome to Radio Reference and Happy New Year!
73 (best wishes in ham lingo), Dave K4EET