[AZKen]

Yes, the adjustment rod needs adjusted to be "longer" to push fork lever more towards rear of truck. Therefore rocking fork forward and pushing throwout brearing deeper into clutch release springs.
It is possible that you have some components installed incorrectly. Sometimes throwout bearing is installed backwards by installer. Reducing it's "reach".....or put the disc in backwards....or throwout bearing facing correctly but flange not "under" the spring clips....and so on. These things WILL cause your failure to disengage problem. You say you have run out of adjustment so the items mentioned are possible.