I'll check the parts numbers when I get home.
There is also another possibility -- if the CH1/CH2 switch fails it can impact the rise time of both channels.
It will not allow proper adjustment of rise time to <0.87 ns.
Typically I can adjust 2465Bs to the mid 0.70ns, some as low as 0.68ns.
It's a tradeoff between risetime and flatness.
When I see the failure I describe above in the channel switch the step response cannot be adjust below 1.2ns.