Need Help finding Lost Transmitter

[SCPD]

One of the old handheld Radio Shack frequency counters might work also
Radio Shack 22-306, LCD Frequency Counter, 1MHz - 1.3GHz

That won't work. You would need to be right on top of the transmitter and the bursts are so fast it's won't register. A longer transmission would be needed as I own one and plus their accuracy is not the greatest.
You get what you pay for.

 

[lmrtek]

I think all batteries will eventually leak

The chemicals reaction never stops

I've had every brand made and they all will leak if left in devices unused for long periods of time