Sorry to answer also tardily.
The probes are OK, they posts 4ohm with my ohmmeter. I also compared with other probes similar, and I always obtain 4ohm. My voltmeter posts 87mV on the output of generator, it does not matter the probe used.
I as noticed as the battery discharges more quickly than front.
I cannot unsolder resistances because it is of micro component then impossible to change.
I am disappointed to note the brittleness of this oscilloscope.
Thank you.