It's a lot of money to spend on something that can be taken off, cleaned, stripped if necessary and rebuilt at home.
I followed one of the guides on this forum earlier in the week. The car wouldn't start properly - found a link with a vid on youtube (in French!). Helped me no end and i had it off and back on within an hour. Mine did have a blanking plate and i removed it and car starts better now. The valve spring was pretty clean and working perfectly so I gave it a bit of a clean and put it back together - quick, easy and effective - love this forum.