Wright Sound AG Phono Preamp questions

I have a wright sound ag phono preamp, main chasis tube complement is 1 x 12au7, 2 x 12ax7, and 2 x ecc99. My quesiton is are the ecc99's part of the original design. When I tap my finger on the ecc99's they ring in the speakers (in fact the chasis and everything connected to the pre can cause a slight high freq ring and I noticed it in the music at higher volumes). My thought was that the tubes must be microphonic but I wasn't even sure if these are the correct tubes for the design (my AG pre was built in 2002). I rolled several au7 and ax7's and I am sure it is not a problem with these tubes. I had a pair of 12bh7's which without knowing if these are a correct sub for the circuit tried them briefly, you can still hear a tap when tapping the tube but not the high freguency ringing sound. If anyone has this pre and can help with any info it would be appreciated, thanks!