We all have encountered them by now. Scenarios like 5U93 Ramsgate Depot to Slade Green Depot.
You drive the scenario perfect. Make the times, stop on the dot. You don't over-speed, have no weird mistakes. In short.... you do the perfect run. And then the end-screen comes up and shows you Silver.

First you redo the scenario, you must have made an error somewhere right. Again you run the perfect run, it doesn't update to Gold still and you realize, this scenario is flawed. And so you hit the community pages and forums. Looking if it is you that is just stupid or if it really is the Scenario and find that it is the scenario... it has been the scenario since the DLC released.

Perhaps you send in a support ticket. And without fail you get the same reply. Bugs are fixed based on priority, this might mean some bugs might be fixed somewhere when they have time or maybe (more likely in the case of scenario bugs) never.

Here is a solution that doesn't require you to drive your train in a dangerous way back and forth on a small piece of track (provided you have that time) but not everyone might agree with this methode and I Understand. However, given the track record (no pun intended) of DTG, I feel justified sharing this methode.

I figured.. what the hay, I give it a try and I started up Cheat Engine (search Google if you don't have it, only get it from the original dot org site)

Start your game. Then start Cheat Engine.
Click the icon below "File" and find the TSW entry, doubleclick this entry.

Now start your scenario as normal and run it till you get AP, pause the game, go to cheat engine and fill the amount of AP in the value field. Now hit "New scan
Continue playing the game until you get AP agai, pause game, fill in new value and hit "Next scan"
Repeat this process until you have 3 or four entries left. Double click the top entry.
You will see it appear in the "Memory View" panel on the bottom. Click on the number below Value
A small pop up will appear. Add the missing amount (you should consider that the AP given for all tasks should add up to 1000, use that to calculate your minimum)

Example: in 5U93 Ramsgate Depot to Slade Green Depot you get a number of green ticks and one entry with 750AP (provided you hit the time and the mark) so you would add 250 points.
The first distance AP is 30 {pause>search using "First Scan")
The second distance AP brings you to 60 {pause>Search using "Next Scan")
The third will bring you to 90 (Pause>Search using "Next Scan")
You should now have 3 or 4 entries.
Double click top entry, double click value amount in lower panel
in the pop up window change value to 340, hit ok, continue play
Next distance AP your number will go up to 370 instead of 120.
Finish Scenario
Get Gold