Stuck in first gear

Have '99 E320 / tiptronic which wont shift out of first. Happened intermittantly for about two days, reset the car by switching off, then restarting. Now the condition seems permanent. The dash indicator display which normally shows the gear is just blank.

A previous post said he'd had a spring replaced in the tran, but was not specific about which one.

Anyone any ideas on this problem?

TVM

PT