[Amps] Source for 8877 amp input tuning coil needed

[Joe Barger]

I'm working on a "classic" W6PO 144 MHz 8877 amp (http://web.wt.net/~w5un/8877-1.htm) .  The input tuning circuit calls for L1 to be wound on a 1/2" diameter form with a white tuning slug (CTC 1538-4-3) .   Does anyone know where I can find this particular form?  Or a reasonable replacement?  The amp currently just has the coil and some unknown ferrite rod stuck in the middle and can't get the SWR between the amp and driver below 3:1.

Thanks

joe n6kk