MX5 Mk1 rust advice

[Birdster]

I picked up a MX5 NA about 6 weeks ago and love it. It had failed it's MOT last year for rusty sills.

offside rear Seat belt anchorage prescribed area is excessively corroded (5.2.6)
offside rear Body or chassis has excessive corrosion, seriously affecting its strength within 30cm of the body mountings (6.1.B.2)

The car was purchased from one of the recommended specialists who is well regarded on here and on Nutz. I'm not naming as I'm not looking to start any arguments, or accusations and I know the rules on here. The garage in question has said they will sort the problem out, so all good.

My concern is that the sills were treated by another company before my supplier picked up the car. So I'm wondering how bad the inner sills are and if there is a way for me to find this out without cutting the outer sill open.

I've just taken this photo today and this seems to have made itself visible since I picked up the car. Considering the price paid I wouldn't feel comfortable shelling out for sill repairs anytime soon. To me this looks like it's just been plated over for the MOT. I'll also raise my concern with the garage when bringing the car in.

[JasperT]

Just sent you a PM Birdster

[drgoatboy]

You can buy a cheap boroscope off ebay and try and have a look in through the rubber bung on the back edge of the sill. It's far from easy to see what's really going on but if the inner sills are Swiss cheese it should be easy to spot.

Edited by drgoatboy on Wednesday 1st June 15:07

[Birdster]

I've replied to your PM, JasperT.

Thanks for the advice, drgoatboy. I'm looking at some on eBay that work with Android phones. They seem to be about £10.

I'm going to take the kick plates off and have a look there as well.

Edited by Birdster on Sunday 5th June 11:58