Late 1994 car transmission warning indicator and won't shift into top gear

I just got my late 1994 XJ40 back on the road after a few months being layed up and when I went to drive it back from my shop I noticed it wasn’t shifting into top gear and the transmission warning indicator on the dash was illuminated. I have see other folks mention cleaning the contacts int the TPS curring the warning lamp problem but I don’t know if that same “solution” also applies to the won’t shift problem too.

Any hints or suggestions would be most welcome since I would like to make this car my daily driver again.

First thing that springs to mind is the fluid level is low. Is it possible the transmission has a leak and during the 'few months layed up ’ the level has dropped ?

This indicates potential problem with converter’s lockup mode, somehow your torque converter is unable to lock up or your tranny is unable to direct sufficient fluid pressure to converter - to lock it up. Top gear (lockup) shall be achievable by regular ride/without excessive pressing the accelleration pedal. Check fluid level first /as i dicated above. Then run it with regular drive style (up to 2100rpm) and check if your banger accelerates without excessive revs between 50-60mph-ish.

When you’ve changed the fluid innyour 4hp24 tranny?
What’s the mileage on your wheels?