Do you have the "OpenChoice Talker Listener" installed in the TekVISA folder on your TLA624? If you do, can you start it up and connect to the analyzer instrument and then try issuing these queries:
SYST:CONF:DEPTH?
SYST:CONF:MAX:DEPTH?
SYST:CONF:SPEED?
SYST:CONF:MAX:SPEED?
If the reported current values are less than reported max values then you can use these commands to set the current values to the max values:
SYST:CONF:DEPTH <DEPTH>
SYST:CONF:SPEED <SPEED>
To enable the modification of the values you first need to to use this command, where <VERSION> is the firmware version reported in response to an *IDN? query:
SYST:PASS:INST:PASS "PitBull<VERSION>"
And after modifying the values you need to use this command for the modified values to take effect, where <TIME> is the current Unix timestamp value, for example from
https://www.unixtimestamp.com/ SYST:PASS:INST:UPD <TIME>
If the battery in the NVRAM chip is dead the speed and depth changes may be lost and revert to their lowest option values when the analyzer is powered off.
More details can be found in this thread:
https://www.eevblog.com/forum/testgear/tla-hacks-)/msg470705/#msg470705