[Ol' Papi]

   
Hello!
This is my very first post - THANKS for letting me come and play. 
I recently acquired a Philco model 484-21 from my granddaughter last July and have been learning and enjoying working on it. Problem is, the FM 1000 tube had an open filament and it seems these tubes are REALLY hard to find. Some suppliers have said they carry them but when I contact them it turns out they're not in stock. I've even paid for some on line and was quickly refunded when they found they didn't have them after all. 
---SO---
I sacrificed the old tube (it was dead anyway) and kept the loctal pin base and created what I thought would be a compatible tube using a 7-pin 6CS6. (See pic)
It seems to be working but I only get 2 FM stations and they are super weak and fuzzy. Plus, some of the voltage values I'm getting when troubleshooting the circuit are way off and the manual keeps leading back to the FM 1000. Anyone know where I can get one, or if there's a work-around for this issue? I've replaced all the paper and e-caps and several resistors, as well as the Z300 transformer, tested the L300 choke for continuity (OK), and I think successfully completed the AM alignment. Oh, and SW is nothing but static. I know I've got a long way to go, but I'm stuck and looking for direction. anything would help.