Shimano 600 STI left shifter

[Dare]

Hey guys,
Hope you can help me with this;
Small shift lever on my left Shimano 600 STI shifter is not returning after shifting the gear, I have to return it manuall, as some spring is not working properly. Is it something easy fixable or do I need new STI shifter?

Tnx in advance...

 

[stringfellow1946]

Remove the lever & all the cables & try flushing out the lever internals with something like GT85 on the work bench & I mean really flushing it out. That some times sorts them out as a last resort.

 

[RichT]

The right hand Ultegra STI shifter on my '94 Dyna-Tech 755Ti is the same

('97 RX100 on a spare bike is the same too)