Stihl weed trimmer very hard to turn over with pull cord

[5030]

One reason I switched to synthetic fuel.

 

[bmg88201]

I have an Echo trimmer. After running the trimmer empty for the winter, I do want the manual says to do and that is put a few cc’s of 2 cycle oil in the spark plug hole and pull the rope a few times and then leave cylinder at top dead center. In the spring I pull the plug again and pull the rope a few times and install the plug and it always fires right up without any resistance.