I'm pretty sure its not a CDI engine. It also is not an engine we ever got in the USA.
You can purchase all new plastic fuel lines fairly cheaply. On the 606 engine it runs about USD$60 for all of them. Or, you could purchase the orings only and replace them yourself. Is an easy DIY job. This link pertains to the 606 again, but the sizes and counts should be very similar.
http://www.peachparts.com/shopforum/showthread.php?t=177588
The fuel lines are clear when new, yellowed if aged. Is kind of nice to have new ones as you can see if any bubbles are present which helps one track down where they come from.
Fuel/Air leaks are fairly common, any MB "diesel" mech ought to have been able to figure that out???
If leaking at DV seals you might want to let a mech do that job as it is a lil bit technical if inexperienced and can cause irreparable damage if done incorrectly.