Clarke original D

Got myself a little Clarke original and I’m quite pleased with the “soft breathy” sound.
The whistle is fairly-well in tune. However, I notice some daylight both under and at one side of the wooden plug. Would the sound be greatly improved with this sealed ?
Any tips on how to fix it ?

Dear Rab
Just use some hard wax (Sealing wax is fine). If the gap is only minimal use French Polish (sets hard like varnish . . . can be applied with brush and prevents block from moving)
Regards . . . Tony P

Thanks Tony,
I used candle wax !!
Slight improvement. The gap was minimal.
Rab.