Tachometer question

Well, I should have expected this. I hooked up my snap on timing light with tach/advance that has been in drawer for probably 15 years and it doesnt work! So I guess its time to buy a new light. I dont think I need a top of the line light so I guess I go shopping at summit and see what I can buy at a decent price. Noting ever seems to work out! lol
I did start it up and the tach appears to be functioning but when engine is off and power is still there the needle is at 8k. As soon as I begin to crank it over it goes to 0 and when engine fires it looks to be working properly. I'll try to get to dads tomorrow and borrow his timing light so I can compare rpms then.
Thanks Rod