If you are using autosampler then one possibility is to increase the syringe cleaning cycles (10 times or more) with DCM before and after the sample injection. You can change this in autosampler method and i hope this will help to some extent to reduce chocking of syringe.

Sample residue are causing chock the syringe. Rinse the syringe properly after use with solvent. 

It's more likely the DCM itself. I'd modify the rinsing cycles to include 5 X hexane then 5 X DCM pre-injection. 5 X DCM then 5X hexane post-injection.

DCM is a very aggressive solvent and shouldn't generally be left to dry-out in syringes. Less aggressive solvents are hexane on tne non-polar side and methanol on the polar side.

Thanks all