I am restoring an old Randall RG50-112 amp.  When I opened the chassis I saw this component in the picture.  It was mounted vertically on the pcb board with one of the leads either clipped intentionally or blown.  I am trying to figure out if this is a simple fuse or a thermistor or a resistor fuse.  Anyone recognize one of these?  No ohmage and no connectivity reading.

I am going to attempt to build my first guitar amp.  I have a transformer whos output is 24.5V RMS.  Would this be enough juice to bias a 12ax7 for the preamp stage?  I think all of the tube preamp schematics ive seen use like 400 volts to power the 12ax7 in the preamp.  Could I use a 12ax7 in a preamp with only 25 volts for a psu?  If it is possible what would be any negatives.