[Amps] AL-80B "Optional" Grid Protection circuitry - identify?

[Charlie]

The AL-80B manual and web site discuss an "optional' grid protection board I 
believe they call it. I am the new owner of a used AL-80B and would like to 
know how I can check if this "optional ' grid protection is in place or not. 
As best I can tell this amp was new in 1997.

I have several photos of the inside on my site listed below. If anyone can 
spot it or tell me what to look for I would be very appreciative. I got on 
this matter after the amp kicked off a couple times on 40M phone.  After 
several moments it was OK again. I am guessing it was this optional circuit. 
TY  73

Charlie
Ham Radio - AD5TH
www.ad5th.com