Given that you know the system was dropped and the problem then occurred, you could either have an issue with the connection of the keyboard assembly to the motherboard or some damage happened to the trackpoint and/or internal cable. Before you tear down the system, try this: with the system off, press firmly down on the "Y" key and the six keys around it. The keyboard connector is located there. Boot the system and see if that helped. If not, then one way to test the keyboard and trackpoint is by running PC Doctor as suggested by RBS. The PC Doctor diagnostic program on the IBM/Lenovo web site is here:http://www-307.ibm.com/pc/support/site. ... YZM3F.html
It's three files that you download and execute in order to create a 3-disk floppy set, which you then boot the system with. If you don't have a floppy, but do have a CD burner and a program which is able to correctly handle .ISO (image) files, then you can download the same program from a file that I host on my site:http://www.kawakami-ca.com/ibm_t2x/ibm_t22_pcdiag.iso
These tests are performed without requiring Windows and essentially checks the basic hardware in the system. After you boot the system, follow the prompts to insert the next floppy and "press a key" to continue (it does this with the CD version as well), under the "Interactive Tests" heading, you will find keyboard and mouse tests. The "keyboard keys" test is basically an on-screen display of all your keyboard keys. Select the "TP 84Key(US/Hebrew)" option. You press each one of the keys and the screen map gets updated with the result. The "Fn" key deserves special mention: it might take two or three presses, or one real long press, before that key is recognized. The "Mouse" test will bring up a display of the status of the mouse (trackpoint) pointer. Move the pointer around the screen and the X and Y coordinates should change. You can also check to see if the mouse buttons are working. Note that there is no test for the center button.
If the mouse and/or keyboard doesn't respond like it should, there is also keyboard test under the "Diagnostics/Systemboard" heading.
You can use the T23 Hardware Maintenance Manual for instructions on how to take the system apart. It's here:http://www-307.ibm.com/pc/support/site. ... IGR-4UYM3F
edit: Something just occurred to me... it's a long shot but it should be checked anyway. Access the BIOS and check the Config / Keyboard/Mouse menu and verify that the TrackPoint entry has Enabled. If it's set to AutoDisable and the system thinks
that an external mouse has been connected, then it will disable the trackpoint.