FrSky conversion or new radio?

[Lozza]

After a bit of advice please.

Been out the game for about 6 years but kept my trusty KO Propo Esprit 2 which I love. Did my first indoor meeting last night and really struggled with interference. It's a new receiver so can rule out that and tried loads if different 40mhz crystals to no avail. Casting my memory back I can remember having a little interference when I raced outdoors so I'm now seriously suspecting I might have an issue we my beloved KO tranny.

My first thought was to do the 2.4ghz FrSky conversion but I'm concerned I might be wasting my money if there is an underlying issue with the tranny.

Or buy a new 2.4ghz system but the few I have looked at just don't feel like anything like the build quality of the KO.

So what do you think.

Try the FrSky conversion?

Or

Buy a new system? ( Would only be able to spend about £150 so any recommendations would be great)

Any advice would be greatly appreciated.

Cheers
Chris