Boot release button has stopped working.

[bouncer]

1998 W202 c200 sport

I put some bags in my boot and closed the lid as normal, then I forgot I needed something out of one of the bags. I tried the button on the key fob as normal. . . . nothing, ok I thought I will use the release button by the gear stick. . . . nothing. Last resort I will use the blade that's inside the key fob.
Yes you guessed it key only went in half way. . . lock full of gunk.
Left it for a few days as I was off to see Ian at 124 Works for a MOT and a bulb. Ian kindly freed off the lock after 20 mins (in the rain as the workshop was full) Sorry Ian.
Car failed the MOT. . ball joints and steering damper, but all kindly sorted by Ian. Forgot to get the boot release sorted by Ian. :Oops:
Ian didn't charge me for freeing the boot lock off either. . . or the bulb for the number plate light.

So any ideas as I fancy having a go myself. Symptoms are:-
Boot wont open from button by gear stick
No red light on said button when the boot is open by the key
There is a funny noise from the petrol filler flap / door that can only be described as woodpecker when I lock it using the remote key. The woodpecker only lasts for about a second.
All the other doors work and lock fine off the key fob.

Where should I look first?

 

[Dec]

The woodpecker is the vacuum pump, you could have a look at this thread here, it will show you how to get at the lock, the vacuum line might be off, worth a quick investigation.

Dec

 

[bouncer]

Thanks for that. . . How good is that write up!
Will have a go this weekend

Thanks
sTeVe

 

[Dec]

If you put your mouth over the white bit where the vacuum line connects, taking the part of the vacuum pump, and either suck or blow, very hard, Lever B should move making a faint click sound (key out of lock)

If it doesn’t move there may be a crack in the brittle plastic vacuum chamber (white bit)
If it dose move, then the lock is o.k. and the problem may be elsewhere, possibly at the vacuum pump, the Yellow line might not be fitted to the pump correctly or it is kinked on its way to the pump.

The pump is located inside rear wing, just behind fuel flap and inside a soft foam box. Remove trim to get access

The lock pictured, may not be exactly the same as yours, there may also be wires connected to your lock.

Dec